Telemetry Equipment

Serial Temperature Sensor Data Logger

noreply@blogger.com (Quick Zone) — Fri, 18 Sep 2009 10:29:00 +0000

This is an 8-pin microcontroller based circuit for temperature data logging via a serial port; small, fast, and acceptably accurate;.between 1 and 4 remote digital temperature sensors, DS18S20 or DS18S20 made by Dallas.

Features
• provides realtime data via the serial port
• interfaces up to 4 x DS18S20 sensors
• accuracy to 0.5 degrees centigrade
• fahrenheit scale selected by a jumper
• no external power required
• data stream easily logged & processed
• over 200m distance for each sensor

Theory of Operation
The program in the microcontroller knows two protocols; the one wire bus used by the DS1820 temperature sensor, and the serial protocol expected by your computer. Once power is applied, the program fetches data from the sensors and sends it to the serial port, repeatedly. The data from the DS1820 arrives in a format peculiar to the sensor. The program calculates the temperature from the data and translates it into human readable ASCII digits. No special program is required on the computer.

Parts List
Where "n" is the number of sensors you wish to use:
• preprogrammed PIC 12C509 microcontroller chip,
• N4003 diode,
• 78L05 voltage regulator,
• 100uF electrolytic capacitor,
• n+1 10uF tantalum capacitors 10V,
• n DS1820 sensors,
• n 2.2k pull-up resistors,
• printed circuit board,
• female 9-pin or 25-pin D connector,
• cable.
Optional parts for transmit indicator (between output pin and ground):
• LED,
• 1k resistor.

Logging Software

Source: Quozl's Temperature Sensor Project

Wireless Mail Messenger

noreply@blogger.com (Quick Zone) — Fri, 18 Sep 2009 04:48:00 +0000

Wireless Mail Messenger can be used if your mailbox standing away from your house so you know exactly when mail arrives. The guy called newbie123 in AVRfreaks have build a nice system which rings a buzzer when mailbox is opened.

Wireless Mail Messenger System consist of two parts. Transmitter and receiver. Both parts are controlled by AT90S2313 AVR microcontroller, that can be easily replaced by Attiny2313. Messenger uses the TLP434A transmitter and the RLP434A receiver from SparkFun.

The wireless mail messsenger transmitter is mounted inside a small plastic radio shack box. Transmitter is placed at the back of the mailbox so it does not interfere with anything. The antenna is routed down through the bottom and just sticks down under the mailbox. When the mail man opens the door to the mailbox, the ground wire is connected to the circuit and the transmitter powers up, transmitting the 4 byte packet to the receiver mounted inside the house. RF Mail Messenger Project Documentation.

Source: AVR freaks

Wireless Servo Controller

noreply@blogger.com (Quick Zone) — Fri, 18 Sep 2009 04:27:00 +0000

Wireless servo controller PIC18LF2550 allows to control two servo motors remotely. It can be used for wireless camera tracking or simply in any robotics project. Receiver and transmitter uses a Laipac TRW-24G 2.4GHz wireless modules.

Any standard servos can be controlled with this device. RF controller controls with a very little latency, which is mainly depending on servos latency. Receiver uses PIC18LF2550 microcontroller with firmware written by using CCS PIC C compile. If put manual joystick control, this could be really powerful remote tracking system.

Receiver Circuit
The source and firmware for the receiver circuit can be found at the bottom of the page. Each section of the circuit is labeled in the schematic. All of the sections and their components are described and discussed below. The part numbers for the components are linked to websites for data and more information when available.

Receiver Power Supply
The >power supply uses a 9 volt battery and a TC1264-3.0V high-accuracy low-dropout linear voltage regulator to provide a stable 3 volt supply for the microcontroller and the transceiver.

Receiver Servos
I used two standard hobby servos that were bought on eBay. Any servos that conform to the standard RC servo >control scheme can be used with this circuit.

Receiver RF-24G Transceiver
The Laipac TRW-24G >2.4GHz transceiver uses a Nordic Semiconductor nRF2401a transceiver chip and includes all of the necessary components. The TRW-24G (also called the RF-24G and TXRX24G) requires a 3 Volt power supply and 3 Volt logic, so running the transceiver at 5 volts is not a viable option.

Receiver Microcontroller
The >microcontroller used was a Microchip PIC18LF2550. I modified the PIC18F2550 Tiny PIC Bootloader assembly file so I could use a 10MHz crystal/resonator at 57,600 baud.

Receiver RS232 Level Converter
The microcontroller USART pins need to be connected to a >RS-232 Level Converter to connect to a PC for firmware updates using the Tiny PIC Bootloader. Otherwise, after initial programming they can be left disconnected.

Transmitter Circuit
The circuit for the >transmitter is exactly the same as the circuit for the 2.4GHz Serial Link; however, a custom firmware is used for the 2-byte payload of the RF-24G (1 byte for each servo).

Source and Firmware
The PIC must initially programmed with the ‘SAC_tinybld18F2550_10MHz_57600′ hex file to program the bootloader on the PIC. Then, using Tiny PIC Bootloader, the hex files can be placed on the chips using the Tiny PIC Bootloader frontend with ‘12h 34h 56h 78h 90h’ in the ‘List of codes to send first:’ in the ‘Options’ menu. Please feel free to contact me if you have any problems.
- SAC_tinybld18F2550_10MHz_57600.asm (hex)
- 18LF2550 RF-24G Serial Servo Transmitter.c (hex)
- 18LF2550 RF-24G Serial Servo Receiver.c (hex)
- RF-24G.c

Source: PIC18LF2550 Wireless Servo Controller

Wireless Temperature Transmitter

noreply@blogger.com (Quick Zone) — Fri, 18 Sep 2009 03:19:00 +0000

Wireless Temperature Transmitter - There is the only way to do if you want to measure temperatures of remote objects. This particular project explains ho to build simple wireless RF temperature transmitter which uses TXM-433 module and Atmega8 while receiver (SILRX-433) is connected to PC via RS232 port.

This wirelss transmitter project is based on AVR wireless RF temperature transmitter and the source code is written for GCC 3.2 compiler. This project is sending data at 4800 baud using RF radio modules, using the Radiometrix TXM-433 and SILRX-433.

You’ll need to select and Atmel AT90S4433 microcontroller for this wireless RF temperature transmitter project, it’s because it has enough flash (4K), RAM (128 bytes) and 6 A/D inputs in a 28 pin narrow package. The best part about this Atmel AT90S4433 is the RAM will turn out to be a bit tight due to the comm buffers and look-up tables.

For the radio’s part, the TXM-433 transmitter and SILRX-433 are the best selection. However, you must first convert the signal from the RF receiver module to RS-232 using a MAX233.

RF Temperature transmitter sends six bytes of data at fixed interval. Module measures three temperature values, light level at photocell and battery voltage. Small Visual Basic program collects data and displays it in a table view. As author (Don Carveth ) says – he can monitor temperature and the light went on of three compost heaps in the back yard by sitting in the room. But this is pretty universal device to use it for other purposes.

Source: Wireless RF Temperature Transmitter

What is PC Data Acquisition?

noreply@blogger.com (Quick Zone) — Fri, 06 Jun 2008 06:34:00 +0000

In general, PC data acquisition is data acquisition from a board or card designed to interface with a personal computer. These boards can be configured to work in a wide variety of configurations including the installation in PCI, ISA or PCMCIA slots. Typical data acquisition products include analog I/O, analog output, digital I/O and serial communications boards that are designed to interface with the bus of a personal computer.

When a PC data acquisition board or card is installed in a personal computer, a wide variety of test automation, measurement, and control applications can be accomplished.

A PC data acquisition system can convert analog signals into a digital output form, which can be manipulated with software. Using software in conjunction with a personal computer, analog data can be displayed, logged, charted, graphed, or stored in memory as needed.

Stored data can later be used and compared with a set of established limits. Control decisions are made if the stored data is at the limit, above or below the limit. With repetitive measurement made by a PC data acquisition system, continuous monitoring and control can be performed.

Based on matching, meeting or exceeding the set limits, a digital control signal (in the form of a single-bit output signal) can be used to turn on or turn off a relay. This in turn can be used to turn on various control elements like fans, pumps, motors, etc.

Alternatively, based on the difference between an input and an established set point, a precise analog output signal can be generated. This signal can be used to provide a complete closed loop control patch, providing continuous control of a process.

Download Free Oscilloscope and Data Logging Software

noreply@blogger.com (Quick Zone) — Fri, 06 Jun 2008 06:18:00 +0000

This demo software allows you to try out our software before you buy a product. The oscilloscope software and data logging software have the same functionality as the full version, but run using simulated data.

Select your software from the list to download your free software

Measurement Systems Data Acquisition

noreply@blogger.com (Quick Zone) — Fri, 06 Jun 2008 05:38:00 +0000

Measurement Systems Limited offers a wide range of data acquisition, data logging, and SCADA hardware, software and systems, to support test , monitoring and control applications.

Measurement Systems' data acquisition products (software, stand alone hardware, and PC boards) provide accurate reliable and cost effective resources for data collection, data analysis, monitoring, testing, data logging and control.

All input/output devices provide fully conditioned direct sensor interfaces for temperature, pressure, strain, distance as well as 4-20ma sensors

The company provides comprehensive pre-sales and post -sales support from the sale of individual products to complete data acquisition systems.

What is data acquisition?

Data acquisition is the collection of data in real time from either analog or digital sensors so that it can be processed or stored by a computer. Data Acquisition Systems normally comprise an input scanner or switch, an analog to digital converter and signal conditioning, to either energise sensors or process them so they can be measured directly in engineering units and a computer to process, log and display the information.

Data Acquisition systems can also form part of a process control system which through the use of appropriate software provides direct digital control of various industrial processes. Similarly they can be used for data logging and process or alarm monitoring.

Data Acquisition Systems are used pervasively in a wide range of industries including electricity generation and transmission, Chemical and Petrochemical, Highways and Transport, Oil and Gas and Steel production, as well as research and development.

Measurement Systems has been in the data acquisition industry since 1981 and has supplied several million data acquisition channels on an international basis. Visit page

OPCNetListener

noreply@blogger.com (Quick Zone) — Fri, 06 Jun 2008 05:04:00 +0000

Use this Server to get a Network - Status monitoring in your PLC for alarm-generation or something else. The Server is watching your network over ICMP (Ping) SNMP. With this it is possible to configure your own Network Management Application in your SCADA System. Now, you can watch also your applications.

License: Demo
Cost: $150.00
Size: 4.12 MB
Download OPCNetListener Free Trial

Honeybee Traffic Counter

noreply@blogger.com (Quick Zone) — Tue, 27 May 2008 18:20:00 +0000

I designed a circuit similar to this one a long time ago to help a beekeeper count the number of bees going into or out of a hive. The low power circuit uses a slotted opto-sensor to detect the passing bees. The circuit advances an electronic counting module whenever a honeybee passes through the sensor. The device only counts the number of bees going through the sensor. A different circuit would be needed to count the number of bees only going out or only coming into the hive.

Visit page

Fluid-Level Sensor

noreply@blogger.com (Quick Zone) — Tue, 27 May 2008 18:12:00 +0000

This Fluid-Level Sensor circuit uses an AC-sensing signal to eliminate electrolytic corrosion on the probes. The AC signal is rectified and used to drive Transistor T1 that drives the relay. The relay is a 12-V type of your choice.

Transistor T1 can also be a TUP. Check out the TUP/TUN document for a large selection of European transistors and what this system is all about. Diodes D2 and D3 are both small signal diodes (1N4148). Diode D1 (1N4001) eliminates transients and possible sparking over the relay coil. Do not use a signal diode for this but a rectifier diode like the 1N4001 or other types of the 1N400x series. Resistor R2 controls the sensitivity. Also your choice. Select one between 10 and 22 Mega-ohm, or use a trim-pot.

The MC14093B is a CMOS quad 2-input NAND Schmitt trigger. The supply voltage can be between 3.0 and 18Vdc. It is pin-for-pin compatible with the CD4093. The capacitors are standard ceramic types but try others if you have them available. (download schematic)

Parts List:

   R1 = 470K                N1,N2 = MC14093B
R2 = 15M*                   T1 = 2N3906 (these will work also: PN200, 2N4413)
C1-C4 = 2N2 (2.2nF)                        (NTE159, ECG159, BC557, BC157, TUP)
D1 = 1N4001                 Ry = Relay (12V or matching supply voltage)
D2,3 = 1N4148             Sensor = Stainless Steel probes, brass, chrome, etc.

Please note:
Unused inputs MUST be tied to an appropriate voltage level, either ground or +12V. In this case, tie input pins 8, 9, 12, and 13 to either ground or +12v. Unused outputs (10 & 11) MUST be left open. You can use them as spares when needed.
In regards to the sensor, use your imagination. Stainless steel would be preferred but try other materials too. Depending on what type of fluid you use it for you naturally would choose your type of sensor which would resist corrosion for that particular fluid. I often use chrome bicycle spokes with very good success. The 'Sensor' works via the capacitive method.

The "RESET" switch in the circuit is optional. The relay can be replaced with anything you like; buzzer, lamps, other relays, etc.

Below are a couple valuable comments from Dave Burton of Burton Systems Software:

Thanks, Tony, for publishing your Fluid-Level Sensor design. I'm using it to detect sewer line plugs (water backing up toward the access port), and hot water heater / clothes washer / AC condensate pump overflows/leaks (water on the basement floor). It works very well.

Also, it says "the 'Sensor' works via the capacitive method." But I don't think that is correct. It would be more accurate to say that, for detecting fluids that are perfect insulators, the circuit CAN be made to work by detecting an increase in capacitance when the fluid replaces air in an air gap in the sensor.

But for the more common case of fluids that are not perfect insulators (like water on my basement floor), the circuit works by detecting resistive conduction through the fluid. It is lowered resistance that is detected, not increased capacitance.

To detect insulating fluids via the capacitive method would require good sized plates separated by an air gap, and careful adjustment of the sensitivity via R2 to distinguish between the possibly small change in capacitance due to the presence of the fluid. The difference might be small because there is only a fairly small differences between the dielectric constants of air and some common fluids. E.g., air has a dielectric constant of 1, and typical oils have dielectric constants of 2 to 5. Note, too, that desire to get a measurably large amount of capacitance leads us to desire that the gap between the plates be small (because the capacitance is inversely proportional to the distance between the plates), but the gap cannot be too small, lest capillary action hold fluid between the plates even after the fluid level has dropped below our sensor.

But to detect dirty water or tap water you can use almost anything: even a pair of bare wire ends several am apart works just fine.

Also, one handy feature not mentioned in the article is that several resistive "sensors" can be hooked up together (in parallel) to detect fluid at any of several different locations. visit page

VO Fuel Controller

noreply@blogger.com (Quick Zone) — Tue, 27 May 2008 17:59:00 +0000

A small circuit to avoid cross contamination of diesel and VO in dual tank vehicles. This is a schematic for a vegetable oil fuel controller, the function is to enforce that VO goes back to the VO tank and diesel goes back to the diesel tank.

Notable Parts:

* K1 is the return fuel line relay
* K2 is the send fuel line relay
* S1 is the primary switch
* S2 is the bypass switch
* S3 is the purge button
* S4 is the On/Off switch
* LED1 is the return line indicator
* LED2 is the send line indicator (download schematic)

Usage
When the vehicle is warm enough so that it can run on vegetable oil turn on S1. The send line will immediately switch to VO and the return line will stay on diesel for a user specified amount of time. To determine correct timing switch your engine to VO and time how long it takes for the diesel to be purge from the system. Now you set the time in the circuit by changing R1 to the correct value based on 1.1 * R1 * C2. To make it easier, I set C2 at 1000µF, so if you want about 45 seconds use the closest value below 45Kohms (45,000 ohms). In the circuit as set up above R1 is 39K ohms giving a timing of just under 45 seconds (1.1 * 39 = 42.9).

When you are a few minutes from home turn off S1 and press S3. By turning off S1 you will switch the send line back to diesel and by pressing S3 you will keep the return line on VO for a user specified amount of time. To set timing use the same value resistor for R4 as you did for R1.

If you stop for a short period of time and the engine is still warm enough to run on VO when you restart it then either switch on S2 for a minute or so or press the purge button. In either case you will bypass the on-delay timer and keep the VO going to the VO tank.
Caveats
Do not expect exact timing from this circuit because capacitors are not perfect and voltage leakage will increase the time to some extent. When I timed the above circuit I found that it varied approximately 2 - 5 seconds (though I used a stopwatch and might have hit the start early or late, so YMMV). The timing can also be affected by length of time of discharge of the capacitors. If you turn off the circuit and turn it on again pretty quickly the timing can be much shorter than expected. I do not consider this an issue because the time it takes for the vehicle to cool down should be well longer than the time it takes for the capacitors to discharge. If this does become a problem use a lower value capacitor and a higher value resistor, for instance you can use a 220uF capacitor and a 180K ohm resistor to get approximately the same amount of time but the timing errors I initially stated may become more noticeable.

Modifications
If you want the circuit to be more automated so you can just switch it on when you turn on the vehicle and it will wait until temperatures are high enough before switching from diesel to VO, just add a thermostat into the circuit directly before S1. Use a NO (normally open) thermostat set to close it's contacts when the desired temperature is reached.
Parts List

* (1) 7805 voltage regulator
* (2) 1N4148 diodes
* (2) SPST switch
* (1) DPST switch
* (1) N/O momentary push button switch
* (2) LM555 timer
* (2) 1000uF polarized capacitors
* (1) 0.01uF non-polarized capacitor
* (3) 0.1uF non-polarized capacitors
* (2) LEDs
* (2) 500 ohm resistors
* (2) 100K ohm resistors
* (2) resistors chosen for timing value (R1 and R4)
* (2) solid state relays capable of handling the current your solenoid valves draw

All capacitors should be rated at least 25 volts, anything higher is fine.
Resistors should be rated for 1/4 watt.
7805 is a generic voltage regulator, if it says 78L05AZ or something it's still fine. visit page

Disclaimer & Terms Of Use:
This circuit is presented as is with no warranty of any kind, I can not be held responsible for any damages you incur either financial or otherwise. This design was created by Seth Koster and may not be used for profit. I hereby grant permission to use this circuit for personal use. Be sure to keep a careful eye on the circuit for a while after you install it to ensure that it is working properly and you installed it correctly. Please use safety equipment when working on electronics!

River Level Monitoring System - RiverSpy2 #2

noreply@blogger.com (Quick Zone) — Tue, 27 May 2008 17:02:00 +0000

How to get started
As you can see from the picture at part #1, the original system was prototyped using veroboard. If you are not familiar with electronics, you will find it easier to build using a printed circuit board (pcb). The layout files are given below. You can order from within the expresspcb program. The MiniBoard service at expresspcb costs US$83 for 3 boards, including a courier service to Ireland. You only need one pcb per gauge but it is not possible to order just one pcb. (If you have a spare pcb, please send it to Daithi Power, Electrical Engineering Dept, University College Cork, Ireland) Alternatively, if you have pcb making facilities of your own, use the express pcb software to print overlays and make a pcb yourself. The right hand side of the pcb snaps off to make the sensor board. The larger left side is used to make the controller board. The controller board measures 3" by 2.5". The sensor part is 0.8" by 2.5".

To assemble and test the circuit, you will need the following tools

* Soldering iron, solder and a small wet sponge to clean the iron
* A small pliers and a snips
* Multimeter for measuring voltages and testing connections

Electrical schematic is here

Bill of materials is here

PCB silkscreen is here

PCB layout is here View and order PCBs using the free software at www.expresspcb.com Three mini-boards cost $51 + shipping.

Assembly drawing of the layout

Sensor
Start with the pressure sensor end. Its the section in the dashed box on the first page of the schematic. Pictures of the construction are shown here. You will need a soldering iron, fine solder, a piece of vero board, a snips and a volt meter. Order the pressure sensor (26PCBFA6D), the INA122, and a small aluminium box from farnell. You will also need a 4m length of 1/4" plastic tubing and a long length of 3 core cable. The length of cable depends on the distance from the sensor to the solar panel at the river bank. Measure the distance with a throw-bag rope and add a few metres. I used shielded cable but ordanary house wiring cable should do fine. Solder the circuit together, power it with a 9V or 12V battery and measure the output using a volt meter. It should read about 0.1V normally and increase when you suck on the tube. If all is ok, put it in the box. You will have to drill holes in the box for the tube and cable. Use a separator to create a cavity for the open end of the sensor as shown in the pictures. Test the circuit again and then fill it with epoxy. Make sure nothing is shorted to the side and that epoxy doesn't get into the open end of the sensor. Test it again while the epoxy is wet by connecting a battery to the far end of the cable. If something has shorted, you will still have a chance to move things around. If all is ok, stick on the lid and let it dry. After it has cured, drop it in a barrel of water and power up the far side of the cable with your battery. If the signal voltage reads somewhere around 1.5V per metre of water, pat yourself on the back.

Before I potted the sensor with epoxy, I screwed the box to one end of a 0.5m length of stainless steel. At the other end of the steel, I drilled some 10m holes to allow me to bolt the sensor to the side of an existing stick gauge at the river bank. The distance between the sensor and 10mm holes allowed the sensor to be mounted under the water without having to drill any holes under water. The system should be installed while the river is at a very low level to ensure the sensor always stays under water.

Pictures of sensor construction
Datasheets for the components can be found at Honeywell , Texas Instruments and Farnell

Controller
Order the controller components and solder them in. The PIC, PT6102 and the INA122 can be obtained as free samples. Look at the Bill of Materials to get order numbers for the rest of the components. Use an ic socket to mount the PIC. The Batt and Phone connectors have extra holes to either use terminal blocks or "Molex" connectors. I find Molex very convenient but if you don't have a crimping tool, go for the terminal blocks. Once assembled you will need access to a PIC programmer such as the ICD2. If you have no way of prorgamming it, send me a PIC and I'll program it for you. Program the PIC using the hex file below and the MPLAB softwar e that you can download from Microchip. During programming, the ICD2 needs to be connected to, and configured to use, an external 9V supply. If you're stuck, send me a PIC and I'll program it for you. Next power up the system using a 12V supply or a battery. The LED should toggle on and off every second.

Hex file for programming PIC is here

Phone

So far, I have built systems using the Siemens M35 and the C45. Any old Siemens phone should do but the connectors on the later ones have gotten smaller so it won't be as easy to solder on the wires. The battery is removed from the phone and it is powered directly by the controller. The AT language used to talk to the internal modem is much the same for all Siemens phones. I have put some pictures of wiring an M35 here . The wire needs to be very fine. I used "wire-wrap" wire. It helps to put some solder on the wire before soldering to the phone. In the pictures shown, the red and black wires are soldered directly to the phone pcb. It is also possible (and easier) to solder them to the contacts that would normally press against the battery. Siemens also make a range of GSM modems such as the TC35. These are made for telemetry applications and would be easy to wire up but would cost you a lot more that an old phone.

Phone connector pin-out here

Pictures of phone wiring here

Installation
A picture of an early RiverSpy rev 2.0 controller is shown below. The latest version is a bit larger and uses through hold components instead of surface mount to make it easier for an inexperienced person to assemble. I'll put up some pictures of the latest rev later.

Terminal block for solar panel or external 12V supply
Molex connector for battery (paralleled with connector 1)
Debugging interface can be used to monitor phone communications using a pc serial port
ICD2 interface for programming the PIC
Molex connector to mobile phone
Molex connector to underwater sensor

The controller, battery and phone should be mounted in a waterproof box. A plastic box allows optimum phone coverage but if vandalism concerns require the use of a metal box, then an external antenna for the phone may be required. A frame should be contructed to mount the solar panel and the box. To optimise solar energy in winter, the solar panel must face south, have a clear view of the sky and be inclined at 70 degrees to the horizontal. Once all of the components have been connected together, configure it as per the installation manual given below.
Send me an email if you need some help.

Installation manual is here

Debugging

I have also put up a schematic of a small circuit that I use for debugging here. All it does is convert a 5V-0V signal to a +12V-12V signal suitable for connecting to the serial port of a pc or laptop. It listens in on the communications between the control board and the phone. I normally connect it to the RX (receive) line of the PIC. RX and GND are at pins 5 and 6 of the connector J4. RX carries the data going from the phone to the PIC. The phone should echo the characters sent from the PIC to the phone so you should see both sides of the conversation. If this is not working, it can also be connected to the TX (transmit) line but this only shows the characters sent by the PIC. The characters can be displayed on the pc using hyperterminal set at COM1, 9600,N,8,1, no flow control. A similar circuit is included in a siemens pc data cable so if you have one of those, just disassemble the connector at the phone end and use that instead. The pinout of the phone connector is given here. Do not connect the TX of the data cable (pin6, RX of the phone) to the phone at the same time as connecting the TX from the PIC. (its like two people trying to talk using walkie talkies at the same time) Also note that pin 3 (Power) and pin 4 (Fbatt+) shown in the phone connector pinout are not the same as the positive terminal of the phone battery (BATT+).

Contacts
If you have questions, contact Daithí Power, visit page

River Level Monitoring System - RiverSpy2 #1

noreply@blogger.com (Quick Zone) — Tue, 27 May 2008 16:47:00 +0000

System Overview
The diagram below gives an overall picture of the system. At the river end, the system is broken into two parts. At the bottom of the river, bolted to an existing stick gauge (or some other convienient location) is a differential pressure sensor. This sensor measures the difference in pressure between the athmosphere and the bottom of the river. To make this differential measurement , one side of the sensor is connected to a breather tube and the other end is open to the surrounding water. The pressure difference P=ρgh , where ρ is density, g is 9.81m/s2 and h is the height between the sensor and the surface of the water. The small signal voltage is amplified by an instrumentation amplifier chip.

The sensor board is connected to the controller board via a 3-core cable. One wire carries a 10V supply to the sensor board. Another wire carries the analog pressure signal back to the controller. The third wire is a ground. The controller board is mounted somewhere on the river bank, in a weather-proof box along with a 12V battery and an old mobile phone. A solar panel is mounted above the box so the location should have an unobstructed view of the southern sky. If vandalism is a concern, the system should perhaps be mounted on top of a tree or a high pole.

Every 15 minutes, the controller board powers up the sensor board and reads the signal once per second for thirty seconds. The measurements are averaged so that the reading is not affected by surges in the water level. Once the reading has been taken, it is stored in memory and the system goes into a low power mode until it is time to take the next reading. Once a day at 09:00, the 96 measurements taken the previous day are collated into a single sms message and sent to an email gateway. The email generated is read by a server which updates the wap and web sites.

The phone that I used is an old Siemens M35, but I think that the command set is the same for all of the M,C and S 25 and 35 phones. The phone does not contain its own battery. (The batteries in those phones were fairly bad anyway) Instead it runs from a supply taken from the 12V battery via a dc-dc converter.

When the system receives a phone call, it examines the caller id to see if an administrator is calling. If it is an admin, the system allows the remote phone to ring once and then hangs up. An sms is sent to the administrator containing the most recent level, the level from 30min previous, the level from 60 min previous and the current state of the 12V battery. If the caller id is not that of an admin, the system will answer the call and give a series of beeps to indicate the most recent level.

Controller board, phone, battery and solar panel mount
The photo below shows the original RiverSpy system with a controller prototyped on veroboard. RiverSpy 2 is laid out on a printed circuited board. The layout file is at the bottom of this page.

When admins ring the phone, the system declines the call and sends back a text of the level now, 30 mins ago and 1 hour ago. When others ring the phone, the system answers the call and gives a series of beeps to indicate the current level.

Next Page

Scriptable Thermometer and Vending Machine

noreply@blogger.com (Quick Zone) — Sun, 25 May 2008 21:50:00 +0000

A unified thermometric controller that can be programmed with simple scripts, integrating the "classic" thermometer/controller pair.
You can build a variety of simple machines with the same hardware and a different script : a charting thermometer, a vending machine that dials your number when empty, a leavening cell...

thermometer with 1°F (0.5C) resolution
four switch inputs, four relay outputs
only an handful of cheap parts
graphic LCD display
script interpreter built-in, can run ASCII programs (basic-like)
6KB non volatile script memory
full screen editor built-in
modular C source code (need a graphic LCD driver?)
Two applications provided:

CHARTING THERMOMETER
Load this script to make Scriptherm draw temperature graphs

SMS PHONE-MAIL ENPOWERED VENDING MACHINE
Load this script to control a refrigerated vending machine that sends you a SMS phone mail message when empty

Downloads: the contest entry with project all circuit details and source code from the National Semiconductor's web site, or the PDF schematic only. Visit Page

Fruit Fly Strobe

noreply@blogger.com (Quick Zone) — Sun, 25 May 2008 09:12:00 +0000

The circuit is a standard pulse generator using two 555 timers (in a single package). Approximate rate adjustment is 1-100 Hz, pulse width is 1 ms-0.5 sec. In single pulse mode, one pulse of the set width is generated when the trigger button is pushed. The button is not debounced, so sometimes you get two pulses. The variable resistor on the left controls rate, the one on the right controls pulse width. The circuit will supply 0.6 amp to the LED, which is above its rating . This means that long duration, high duty-cycle bursts can burn it out. On the other hand, it is very bright.

A circuit board was designed using ExpressPCB software. The image of the board is below. The design file requires a free download from ExpressPCB (for windows only). Traces on the top of the board are red, and on the bottom are green. Component values are given on yellow, but are not printed on the board, if you use the cheapest board production service. There are actually two copies of the circuit on one production board (see design file), so you need to cut them apart with a band saw.

Parts list:

LED is a one watt Cree XLamp™ 7090WBL ordered from All Electronics, part number LED-112 (blue light) or LED-110 (white).
BUZ71A is an N-channel power MOSFET ordered from All Electronics, part number BUZ71A
The IC is a NE556 dual timer, digikey part number 296-6504-5-ND, or digikey part number LM556CN-ND
All surface mount parts are 1206 sized parts from digikey. Capacitors are type X7R from kit part number PCC6-KIT-ND. Resistors are 5% tolerance, thick film, from kit part number CR1A-KIT-ND .
Variable resistors are Audio Taper Potentiometers jameco part number 255441; manufacturer's part number RV24A-10-15R1-A100K
Push button and switches can be any small, low power switches. The push button (Trigger) should be normally-open.
Battery pack consisted of 4 AA cells (6 volts nominal). The battery holder was similar to digikey part number BH24AAW-ND.
Box is a 5"x2.5"x2" ABS Speedy box, jameco part number 18913

Construction

Solder the surface mount components first, then a socket for the 556 ic. Put the 4.7 microfarad through-hole capacitor and MOSFET on the board last. Controls were mounted on the front panel, then wired to the board. A small plastic insert held the battery pack at one end of the box. The box is small enough that the printed circuit board was simply pushed against the bottom of the box by the connecting wires. To fit the small box I used, the MOSFET had to be bent flat toward the right side of the board, as you can see in the photo below.

Wires going to the controls were twisted to minimize noise. HOWEVER, it may be necessary to fiddle with the placement of the wires in the bos in order to keep the LED from latching on. When you first turn on the circuit be ready to immediately. visit page

Telemetry Transmitter for Small Animal

noreply@blogger.com (Quick Zone) — Sun, 25 May 2008 08:48:00 +0000

The goal of this project was to build a small, cheap, light-weight telemetry transmitter to attach to a small animal. This version uses a commercial, low-power transmitter, the Radiotronix RCT-433-AS. The design worked well, but has a relatively high current draw of about 500 microamps. A CR1620 lithium coin cell runs the circuit for about a week. The current version uses a pair of CMOS oscillators to produce a chirp once per second.

The circuit shown above has two standard CMOS multivibrators. The second is gated by the first. The duty cycle of the first oscillator is about 1%, or 10 mSec every second. A logic-high at the telemetry transmitter control turns it on.

The circuit board was layed out using ExpressPCB software. You will need to download a copy to view the design file. The components are all surface mount. The dots shown below are on a 0.1 inch grid.

Note the antenna lead at the lower left. At 433 MHz (70 cm wavelength) a quaterwave antenna should be 17 cm long. The battery is partly shown at the right. It is a CR1620 lithium cell, but any 3 volt source may be used. The transmitter module sticks out to the left. Visit page

Intelligent Remote Positioner (Motor Control)

noreply@blogger.com (Quick Zone) — Fri, 23 May 2008 07:57:00 +0000

INTRODUCTION
The excellent cost/performance ratio of the PIC16C5X makes it well suited as a low-cost proportional D.C. actuator controller. This application note depicts a design for a remote intelligent positioning system using a D.C. motor (up to 1/3 hp) run from 12V to 24V. The position accuracy is one in eight bits or 0.4%. The PIC16C5X receives its command and control information via a Microwire(R) serial bus. However, any serial communication method is applicable.

IMPLEMENTATION
The PIC16C5X based controller receives movement commands from a host, compares them to the actual position, calculates the desired motor drive level and then pulses a full H-bridge (Figure 2). In this way it serves as a remote intelligent positioner, driving the load until it has reached the commanded position. It can be used to control any proportional D.C. actuator (i.e., D.C. motor or proportional valve).

This system is ideally suited for remotely positioned valves and machinery. It can be used with D.C. motors to easily automate manual equipment. Because of the 5-wire serial interface, the positioner can be installed near its power supply and load. The remote intelligent positioner can then be linked to the central control processor by a small diameter easily routed cable. Since the positioner is running its own closed-loop PID algorithm (Figure 3), the host central processor needs only to send position commands and is therefore free to
service the user interface, main application software and command multiple remote positioners.

The limit switch inputs provide a safety net which keeps the system from destroying itself in the event that the feedback device is damaged. The optional current sense input can be used to determine if the load has jammed and prevent overheating of the actuator and drive electronics.

The commanded positions are presented to the PIC16C5X via a microwire type protocol at bit-rates of up to 50 Kbs for a 4 MHz part. As currently implemented in this application note, the position request is the only communication. There are several
variable locations available which could be used to down-load the loop gain parameters, read positioner information, or set a current limit. The host that is sending the position request must set the chip select low, and wait for the PIC16C5X to raise the "busy" (DO) line high. At this point, eight data bits can be clocked into the PIC16C5X. The requested position is sent most significant bit first and can be any 8-bit value. Values 1 through 255 represent valid positions with 0 being
reserved for drive disable. The PIC16C5X acquires its data by way of a
Microwire(R)

A/D converter. This part was chosen for low cost while providing adequate performance. In Figure 1 the second channel of the A/D converter is shown connected to a peak current detector. If the user desires, the PIC16C5X could monitor and protect the motor from overcurrent conditions by monitoring the second channel.

Download: Documentation Source Code Visit Page

Inexpensive Wireless Telemetry For Animal Tracking

noreply@blogger.com (Quick Zone) — Fri, 23 May 2008 07:02:00 +0000

This project explored the feasibility of creating a cost-effective transmitter receiver pair to replace commercially available 150 MHz devices used in animal telemetry. Distance measurements of test circuits transmitting at 418 MHz were taken over clear ground and in forested areas. These measurements show a range of 300-400 feet in forest underbrush and acceptable dropoff over distance, demonstrating that 70 cm radiation can be used in this application. For testing, a 418 MHz Yagi antenna was constructed and shown to exhibit strong directionality and approximately 20 dB gain in the forward direction.

Once it was determined that 400 MHz radiation is capable of forest penetration to the range specified, the telemetry transmitter design was optimized for greater battery life. After exploring several potential oscillator designs for transmitter input, an op-amp circuit was designed with appropriate PCB layout. A 433 MHz transmitter/receiver pair was constructed and tested to show signal range at the same level as earlier measurements at significantly lower power consumption rate. The final transmitter has a total current draw of 70 uA. This translates to roughly one and a half months of continuous operation using freely available 70 mAh lithium-ion coin batteries. Components for the transmitter receiver pair are available at considerably less cost than commercial devices, with component cost for each transmitter at roughly ten dollars and for the receiver at less than twenty dollars.

Original document Wireless Telemetry: Christopher Yeou - Hwa Chau

Building a Basic Stamp II Temperature Logger

noreply@blogger.com (Quick Zone) — Thu, 22 May 2008 17:18:00 +0000

Introduction
This project will show you how to build Temperature Logger using a Stamp II connected to a PC serial port. I was planing on using the DS1620, but used a LM335 temperature sensor because it only needs a two wire interface and it is easy to waterproof. All i did to waterproof it was to put some heat sink tubing around the 3 wires then around the hole sensor.

Here is a screen shot of the Visual Basic 5 Program. The program still has some bugs, but its just error trapping things, like clicking the connect button with no com port selected will give you a error. I will fix that later, or you can do it your self. The software is available to anyone who wants it, feel free to modify it and way you wish. This program is made in Visual Basic 5, but will work fine in Visual Basic 6.

The program will update the current temperature every one second on the PC screen and will save it to a txt file on the Hard Drive every five minutes, along with the time and date. It will also display max and min temperature and max and min pressure for a 24 hour period, and plots pressure and temperature for a 24 hour period.

Weather Monitor logger Schematic
The LM335 is a presision temperature sensor, its output is a linear relationship (10mV/Kelvin). The LM335 is a zener diode that its voltage drop across increase as temperature increases. Note that there is a 2.2 Kohm current limiting resistor. Without the limiting resistor the LM335 will have to dissipate too much heat and increase the temperature reading. The formula for calculating the output of the LM335 is

Temp(in C) = (Vout*100)-273.15

To convert that to F it would be

Temp(in F) = (temp*1.8)+32

From a range of -20C(68F) to 45C(113F) the output range is about 1.3V's. However the ADC has a range of 4.096V, which is fine but if you would like to get a better resolution(more accurate temp reading) you could use a op amp circuit to make the output votlage be 0 V at -20C and 4V at 45C. Connecting it directly will, however, give you 0.1 C/1mV or .05F/1mV which is very good, but the opamp circuit would be more work, but would give you close to .01F/1mV. I dont think it really worth it , but i just thought i might mention it. I also just added a MPX4115 pressure sensor to monitor pressure as well, but i havnt updated the schematic with yet.

Note that i didnt show the connection to the PC, this is showen on the intro page.

Downloads
1 Kb BASIC Stamp II Code
3 Kb Visual Basic 5 Code
0 Kb Templogger Setup program Coming soon.
100 Kb Datasheet for the LM335

Note: The Visual Basic code is the code you can edit in Visual Basic 5, the Templogger program is a setup file to install vbtemplog.exe. If you dont have Visual Basic 5 you can install this and use the Temp Logger program. You cant modifiy it though.

Conclusion
With a little more work you could use this to read up to 8 different temperatures in different areas. This would require a lot more code on the Visual Basic side of it because the string of data coming in would be 32 bits long, however not impossible. In the future i plan on adding a MPX4115 pressure sensor to this and log the pressure as well.

Voice Activated Switch

noreply@blogger.com (Quick Zone) — Wed, 21 May 2008 21:09:00 +0000

This circuit uses an MC2830 to form a voice activated switch (VOX). A traditional VOX circuit is unable to distinguish between voice and noise in the incoming signal. In a noisy environment, the switch is often triggered by noise, or the activation sensitivity must be turned down.

This circuit overcomes this weakness. The switch is activated by voice level above the noise and not activated by background noise. This is done by utilizing the differences in voice and noise waveforms. Voice waveforms generally have a wide range of variation in amplitude, whereas noise waveforms are more stable. The sensitivity of the voice activation depends on the value of R6. The voice activation sensitivity is reduced from 3.0dB to 8.0dB above the noise if R6 changes from 14k to 7.0k.

RF Dual DC Motors Controller

noreply@blogger.com (Quick Zone) — Wed, 21 May 2008 20:55:00 +0000

The transmitter circuit consists of WZ-X01 RF module, Holtek HT-640 encoder and 8 bit A/D converter. U1 ADC0804 converts the analog voltage to digital data, U2 encodes that data (D0~D6) along with D6, D7 and transmitting through the RF transmitter module.

The potentiometer VR1 varies the voltage to the A/D U1 pin6, since only the lower 6 bits are used; the trim pot VR2 has to adjust so that the maximum input to the U1 will not exceed 1.25V. The S2 (D6) and S3 (D7) are used for controlling the rotation direction of the motors. S1 set the transmitter address; this address has to match with the address of the decoder circuit.

The receiver module WZ-R01 receives the data from the transmitter and feeds that data to the decoder U1 (HT-648L); the 8bit data will then be decoded. The first two significant bits D7 and D6 control the motor rotation direction. The lower 6 bits vary the duty cycle of the output pulse. U2 is a 12bit counter; it is configured so that it will reset itself every 64 counts. The oscillation circuit forms by U4c, U4d and U4e providing approximately 1MHz clock to the counter U2.

The 8-bit magnitude comparator U3 (74HCT688) compares the data from the counter U2 with the data of the decoder U1; when data from both are match, it will output a pulse to cause the D-flip flop U5 changing it's state.

By varying the data output of the decoder from 0-64; the duty cycle of the output pulse at U5 pin5 can also change from 0-100%. This output pulse will then be used to control the speed of the motor.

With 1MHz clock input the PWM frequency output is about 15.6KHz. The motor has less audible noise when run at a frequency higher than 10KHz.You may need to change the frequency depending on the motor you're going to use.

The motor driver section is very straightforward; the LMD18200 can handle 3A continuous motor current and 6A peak. In this circuit the sign/magnitude mode of operation is implemented. The current sensing circuit provides protection to both the driver and the motor; it set at 2A max. You can change the current limit by using a different current sensing resistor value (see LMD18200 data sheet for details) or the voltage reference at pin6 of the U7Op-Amp

All of the components use in this project can be purchased from us. Email us at wzmicro@worldnet.att.net, if you have any questions or comments. Your feedback is mostly appreciated.

T/Mon NOC — An Integrated SCADA Monitoring and Control Solution

noreply@blogger.com (Quick Zone) — Tue, 20 May 2008 09:00:00 +0000

My company, DPS Telecom, manufactures T/Mon NOC, a master unit that serves as the core of an integrated SCADA system for all your equipment. T/Mon NOC can meet all the criteria I’ve listed for a superior SCADA master … and can do a whole lot more.

What Can T/Mon NOC Do for You?

T/Mon NOC provides a single, one-screen view of all your monitored equipment. T/Mon NOC will tell you 100% for certain whether anything has gone wrong with any of your monitored equipment, so you can be absolutely sure there are no secret problems anywhere in your system.
T/Mon NOC can monitor up to 1 million alarmpoints, giving you ample capacity to monitor everything in your facilities.
T/Mon NOC presents information in simple, plain English, including detailed text messages telling system operators exactly what to do in case of an emergency.
T/Mon NOC’s Derived Alarms and Derived Controls let you automate every aspect of your systems using simple Boolean logic.
You can filter alarms for the needs of different users. You can select which alarms are immediately forwarded to technicians via pager and email, which alarms can be viewed locally on the T/Mon NOC console, and which alarms are just logged to a history file for recording and later analysis.
At every level of your organization, people can see the information they want without being bombarded with nuisance alarms. Actually, this list just scratches the surface of T/Mon NOC’s capabilities. For more information about what T/Mon NOC can do for you, see the T/Mon NOC Product Data Sheet on page 16.

How Can You Know That T/Mon NOC Will Work for You?
T/Mon NOC is not a new or untested product. T/Mon units have been in the field for years, successfully performing for clients who need stable, bulletproof monitoring and control to support their mission-critical operations.

What Do Real People Who Use T/Mon NOC Say?
“DPS Telecom gave us a reliable way of accessing a variety of equipment, regardless of the brand or provider. We now have a common interface for our existing system.” Harold Moses, KMC

Telecom “DPS told us we didn’t have to pay if it didn’t work. It works and it’s sweet.” Glenn Lippincott, Southern Company

“It’s hard to find companies with the intelligence and aptitude to meet the customer’s exact needs, and I believe that is what DPS is all about.” Lee Wells, Pathnet

Why You Need Help With Your SCADA Implementation
Implementing an SCADA system can seem deceptively easy — you just look on the Web, find a few vendors, compare a few features, add some configuration and you’re done, right?

The truth is, developing a SCADA system on your own is one of the riskiest things you can do. Here are some of the typical problems you might face if you don’t get expert advice when you’re designing your system:

Implementation time is drawn out: It’s going to take longer than you think. Network monitoring is a highly technical subject, and you have a lot to learn if you want a successful implementation. And anytime you are trying to do something you’ve never done before, you are bound to make mistakes — mistakes that extend your time and your budget beyond their limits.
Resources are misused: If you’re not fully informed about your options for systems integration, you may replace equipment that could have been integrated into your new system. Rushing into a systemwide replacement when you could have integrated can cost you hundreds of thousands of dollars.
Opportunities are missed: If you install a new SCADA system today, you’re committing your company to that system for as long as 10 to 15 years. Many companies design what they think is a state-of-the-art SCADA system — and then find that their technology is actually a generation behind.

How to Evaluate SCADA Systems and Hardware

noreply@blogger.com (Quick Zone) — Tue, 20 May 2008 08:46:00 +0000

SCADA can do a lot for you — but how do you make sure that you’re really getting the full benefits of SCADA? Evaluating complex systems can be tricky — especially if you
have to learn a new technology while still doing your everyday job.

But you’ve got to be able to make an informed decision, because the stakes are incredibly high. ASCADAsystem is a major, business-to-business purchase that your company will live with for maybe as long as 10 to 15 years. When you make a recommendation about a permanent system like that, you’re laying your reputation on the line and making a major commitment for your company.

And as much as SCADA can help you improve your operations, there are also some pitfalls to a hasty, unconsidered SCADA implementation:

You can spend a fortune on unnecessary cost overruns
Even after going way over budget, you can STILL end up with a system that doesn’t really meet all your needs
Or just as bad, you can end up with an inflexible system that just meets your needs today, but can’t easily expand as your needs grow

So let’s go over some guidelines for what you should look for in a SCADA system.

What to Look for in a SCADA RTU
Your SCADA RTUs need to communicate with all your on-site equipment and survive under the harsh conditions of an industrial environment. Here’s a checklist of things you should expect from a quality RTU:

Sufficient capacity to support the equipment at your site … but not more capacity than you actually willuse. At every site, you want an RTU that can support your expected growth over a reasonable period of time,but it’s simply wasteful to spend your budget on excess capacity that you won’t use.
Rugged construction and ability to with standextremes of temperature and humidity. You knowhow punishing on equipment your sites can be. Keep in mind that your SCADA system needs to be the mostreliable element in your facility.
Secure, redundant power supply. You need your SCADA system up and working 24/7, no excuses. Your RTU should support battery power and, ideally, two power inputs.
Redundant communication ports. Network connectivityis as important to SCADA operations as a power supply. A secondary serial port or internal modem will keep your RTU online even if the LAN fails. Plus, RTUs with multiple communication ports easily support LAN migration strategy.
Nonvolatile memory (NVRAM) for storing software and/or firmware. NVRAM retains data even whenpower is lost. New firmware can be easily downloaded to NVRAM storage, often over LAN — so you can keep your RTUs’ capabilities up to date without excessive site visits.
Intelligent control. As I noted above, sophisticated SCADA remotes can control local systems by themselves according to programmed responses to sensor inputs. This isn’t necessary for every application, but it does come in handy for some users.
Real-time clock for accurate date/time stamping of reports.
Watchdog timer to ensure that the RTU restarts after a power failure.

What to Look for in a SCADA Master
Your SCADA master should display information in the most useful ways to human operators and intelligently regulated your managed systems. Here’s a checklist of SCADA master must-haves:

Flexible, programmable response to sensor inputs. Look for a system that provides easy tools for programmingsoft alarms (reports of complex events that track combinations of sensor inputs and date/time statements) and soft controls (programmed control responses to sensor inputs).
24/7, automatic pager and email notification. There’s no need to pay personnel to watch a board 24 hours a day. If equipment needs human attention, the SCADA master can automatically page or email directly to repair technicians.
Detailed information display. You want a system that displays reports in plain English, with a complete description of what activity is happening and how youcan manage it.
Nuisance alarm filtering. Nuisance alarms desensitize your staff to alarm reports, and they start to believe that all alarms are nonessential alarms. Eventually they stop responding even to critical alarms. Look for a SCADA master that includes tools to filter out nuisance alarms.
Expansion capability. A SCADA system is a longterm investment that will last for as long as 10 to 15 years. So you need to make sure it will support your future growth for up to 15 years.
Redundant, geodiverse backup. The best SCADA systems support multiple backup masters, in separate locations.. If the primary SCADA master fails, a second master on the network automatically takes over, with no interruption of monitoring and control functions.
Support for multiple protocols and equipment types. Early SCADA systems were built on closed, proprietary protocols. Single-vendor solutions aren’t a great idea — vendors sometimes drop support for their products or even just go out of business. Support for multiple open protocols safeguards your SCADA system against unplanned obsolescence

How SCADA Systems Work?

noreply@blogger.com (Quick Zone) — Tue, 20 May 2008 08:29:00 +0000

A SCADA system performs four functions:
1. Data acquisition
2. Networked data communication
3. Data presentation
4. Control

These functions are performed by four kinds of SCADA components:

Sensors (either digital or analog) and control relays that directly interface with the managed system.
Remote telemetry units (RTUs). These are small computerized units deployed in the field at specific sites and locations. RTUs serve as local collection points for gathering reports from sensors and delivering commands to control relays.
SCADA master units. These are larger computer consoles that serve as the central processor for the SCADA system. Master units provide a human interface to the system and automatically regulate the managed system in response to sensor inputs.
The communications network that connects the SCADA master unit to the RTUs in the field.

The World’s Simplest SCADA System
The simplest possible SCADA system would be a single circuit that notifies you of one event. Imagine a fabrication machine that produces widgets. Every time the machine finishes a widget, it activates a switch. The switch turns on a light on a panel, which tells a human operator that a widget has been completed.

Obviously, a real SCADA system does more than this simple model. But the principle is the same. A full-scale SCADA system just monitors more stuff over greater distances.

Let’s look at what is added to our simple model to create a fullscale SCADA system:

Data Acquisition
First, the systems you need to monitor are much more complex than just one machine with one output. So a real-life SCADA system needs to monitor hundreds or thousands of sensors.
Some sensors measure inputs into the system (for example, water flowing into a reservoir), and some sensors measure outputs (like valve pressure as water is released from the reservoir). Some of those sensors measure simple events that can be detected by a straightforward on/off switch, called a discrete input (or digital input). For example, in our simple model of the widget fabricator, the switch that turns on the light would be a discrete input. In real life, discrete inputs are used to measure simple states, like whether equipment is on or off, or tripwire alarms, like a power failure at a critical facility.

Some sensors measure more complex situations where exact measurement is important. These are analog sensors, which can detect continuous changes in a voltage or current input. Analog sensors are used to track fluid levels in tanks, voltage levels in batteries, temperature and other factors that can be measured in a continuous range of input. For most analog factors, there is a normal range defined by a bottom and top level. For example, you may want the temperature
in a server room to stay between 60 and 85 degrees Fahrenheit. If the temperature goes above or below this range, it will trigger a threshold alarm. In more advanced systems, there are four threshold alarms for analog sensors, defining Major Under, Minor Under, Minor Over and Major Over alarms.

Data Communication
In our simple model of the widget fabricator, the “network” is just the wire leading from the switch to the panel light. In real life, you want to be able to monitor multiple systems from a
central location, so you need a communications network to transport all the data collected from your sensors.

Early SCADA networks communicated over radio, modem or dedicated serial lines. Today the trend is to put SCADAdata on Ethernet and IP over SONET. For security reasons, SCADA data should be kept on closed LAN/WANs without exposing
sensitive data to the open Internet.

Real SCADA systems don’t communicate with just simple electrical signals, either. SCADA data is encoded in protocol format. Older SCADA systems depended on closed proprietary protocols, but today the trend is to open, standard protocols and protocol mediation.

Sensors and control relays are very simple electric devices that can’t generate or interpret protocol communication on their own. Therefore the remote telemetry unit (RTU) is needed to
provide an interface between the sensors and the SCADA network. The RTU encodes sensor inputs into protocol format and forwards them to the SCADA master; in turn, the RTU receives control commands in protocol format from the master and transmits electrical signals to the appropriate control relays.

Data Presentation
The only display element in our model SCADA system is the light that comes on when the switch is activated. This obviously won’t do on a large scale — you can’t track a lightboard of a thousand separate lights, and you don’t want to pay someone simply to watch a lightboard, either.

A real SCADA system reports to human operators over a specialized computer that is variously called a master station, an HMI (Human-Machine Interface) or an HCI (Human- Computer Interface).

The SCADA master station has several different functions. The master continuously monitors all sensors and alerts the operator when there is an “alarm” — that is, when a control factor is operating outside what is defined as its normal operation. The master presents a comprehensive view of the entire managed system, and presents more detail in response to user requests. The master also performs data processing on information gathered from sensors — it maintains report logs and summarizes historical trends.

An advanced SCADA master can add a great deal of intelligence and automation to your systems management, making your job much easier.

Control
Unfortunately, our miniature SCADA system monitoring the widget fabricator doesn’t include any control elements. So let’s add one. Let’s say the human operator also has a button on his control panel. When he presses the button, it activates a switch on the widget fabricator that brings more widget parts into the fabricator.

Now let’s add the full computerized control of a SCADA master unit that controls the entire factory. You now have a control system that responds to inputs elsewhere in the system. If the machines that make widget parts break down, you can slow down or stop the widget fabricator. If the part fabricators are running efficiently, you can speed up the widget fabricator.

If you have a sufficiently sophisticated master unit, these controls can run completely automatically, without the need for human intervention. Of course, you can still manually override the automatic controls from the master station.

In real life, SCADA systems automatically regulate all kinds of industrial processes. For example, if too much pressure is building up in a gas pipeline, the SCADAsystem can automatically open a release valve. Electricity production can be adjusted to meet demands on the power grid. Even these real-world examples are simplified; a full-scale SCADA system can adjust the managed system in response to multiple inputs.

What is SCADA, and What Can It Do for You?

noreply@blogger.com (Quick Zone) — Tue, 20 May 2008 08:14:00 +0000

What is SCADA, and What Can It Do for You?
SCADA is not a specific technology, but a type of application. SCADA stands for Supervisory Control and Data Acquisition — any application that gets data about a system in order to control that system is a SCADA application. A SCADA application has two elements:

The process/system/machinery you want to monitor a control — this can be a power plant, a water system, a network, a system of traffic lights, or anything else.
A network of intelligent devices that interfaces with the first system through sensors and control outputs. This network, which is the SCADA system, gives you the ability to measure and control specific elements of the first system.

You can build a SCADA system using several different kinds of technologies and protocols. This white paper will help you evaluate your options and decide what kind of SCADA system is best for your needs.

Where is SCADA Used?
You can use SCADA to manage any kind of equipment. Typically, SCADA systems are used to automate complex industrial processes where human control is impractical — systems where there are more control factors, and more fast-moving control factors, than human beings can comfortably manage.

Around the world, SCADA systems control:

Electric power generation, transmission and distribution: Electric utilities use SCADA systems to detect current flow and line voltage, to monitor the operation of circuit breakers, and totake sections of the power grid online or offline.
Water and sewage: State and municipal water utilities use SCADA to monitor and regulate water flow, reservoir levels, pipe pressure and other factors.
Buildings, facilities and environments: Facility managers use SCADA to control HVAC, refrigeration units, lighting and entry systems.
Manufacturing: SCADA systems manage parts inventories for just-in-time manufacturing, regulate industrial automation and robots, and monitor process and quality control.
Mass transit: Transit authorities use SCADA to regulate electricity to subways, trams and trolley buses; to automate traffic signals for rail systems; to track and locate trains and buses; and to control railroad crossing gates.
Traffic signals: SCADA regulates traffic lights, controls traffic flow and detects out-of-order signals.

As I’m sure you can imagine, this very short list barely hints at all the potential applications for SCADA systems. SCADA is used in nearly every industry and public infrastructure project — anywhere where automation increases efficiency. What’s more, these examples don’t show how deep and complex SCADA data can be. In every industry, managers need to control multiple factors and the interactions between those factors. SCADA systems provide the sensing capabilities and the computational power to track everything that’s relevant to your operations.

What’s the Value of SCADA to You?
Maybe you work in one of the fields I listed; maybe you don’t. But think about your operations and all the parameters that affect your bottom-line results:
• Does your equipment need an uninterrupted power supply and/or a controlled temperature and humidity environment?
• Do you need to know — in real time — the status of many different components and devices in a large complex system?
• Do you need to measure how changing inputs affect the output of your operations?
• What equipment do you need to control, in real time, from a distance?
• Where are you lacking accurate, real-time data about key processes that affect your operations?

Real-Time Monitoring and Control Increases Efficiency and Maximizes Profitability
Ask yourself enough questions like that, and I’m sure you can see where you can apply a SCADA system in your operations. But I’m equally sure you’re asking “So what?” What you really want to know is what kind of real-world results can you expect from using SCADA.

Here are few of the things you can do with the information and control capabilities you get from a SCADA system:
• Access quantitative measurements of important processes, both immediately and over time
• Detect and correct problems as soon as they begin
• Measure trends over time
• Discover and eliminate bottlenecks and inefficiencies
• Control larger and more complex processes with a smaller, less specialized staff.

A SCADA system gives you the power to fine-tune your knowledge of your systems. You can place sensors and controls at every critical point in your managed process (and as SCADA technology improves, you can put sensors in more and more places). As you monitor more things, you have a more detailed view of your operations — and most important, it’s all in real time.

So even for very complex manufacturing processes, large electrical plants, etc., you can have an eagle-eye view of every event while it’s happening — and that means you have a knowledge base
from which to correct errors and improve efficiency. With SCADA, you can do more, at less cost, providing a direct increase in profitability.