Telemetry Equipment

Serial Temperature Sensor Data Logger

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.

Wireless Mail Messenger

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 Servo Controller

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

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?

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.

Download Free Oscilloscope and Data Logging Software

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.

Measurement Systems Data Acquisition

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.

OPCNetListener

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.

Honeybee Traffic Counter

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.

Fluid-Level Sensor

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 = MC14093BR2 = 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[...]

VO Fuel Controller

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)UsageWhen 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.CaveatsDo 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.ModificationsIf 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 drawAll 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 pageDisclaimer & 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 in[...]

River Level Monitoring System - RiverSpy2 #2

Tue, 27 May 2008 17:02:00 +0000

How to get startedAs 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 connectionsElectrical schematic is hereBill of materials is herePCB 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 SensorStart 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 constructionDatasheets for the components can be found at Honeywell , Texas Instruments and FarnellControllerOrder 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 [...]

River Level Monitoring System - RiverSpy2 #1

Tue, 27 May 2008 16:47:00 +0000

System OverviewThe 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 mountThe 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

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) resolutionfour switch inputs, four relay outputs only an handful of cheap parts graphic LCD displayscript interpreter built-in, can run ASCII programs (basic-like)6KB non volatile script memoryfull screen editor built-in modular C source code (need a graphic LCD driver?)Two applications provided:CHARTING THERMOMETERLoad this script to make Scriptherm draw temperature graphsSMS PHONE-MAIL ENPOWERED VENDING MACHINELoad this script to control a refrigerated vending machine that sends you a SMS phone mail message when emptyDownloads: 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

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-NDAll 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 ConstructionSolder 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

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)

Fri, 23 May 2008 07:57:00 +0000

INTRODUCTIONThe 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.IMPLEMENTATIONThe 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 toservice 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 severalvariable 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 beingreserved for drive disable. The PIC16C5X acquires its data by way of aMicrowire(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

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

Thu, 22 May 2008 17:18:00 +0000

IntroductionThis 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 SchematicThe 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 isTemp(in C) = (Vout*100)-273.15To convert that to F it would beTemp(in F) = (temp*1.8)+32From 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 Code3 Kb Visual Basic 5 Code0 Kb Templogger Setup program Coming soon.100 Kb Datasheet for the LM335Note: 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.ConclusionWith 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

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.

RF Dual DC Motors Controller

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-AmpAll 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

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, KMCTelecom “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, PathnetWhy You Need Help With Your SCADA ImplementationImplementing 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 SCA[...]

How to Evaluate SCADA Systems and Hardware

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 youhave 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 overrunsEven after going way over budget, you can STILL end up with a system that doesn’t really meet all your needsOr 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 growSo let’s go over some guidelines for what you should look for in a SCADA system.What to Look for in a SCADA RTUYour 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 MasterYour 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, automati[...]

How SCADA Systems Work?

Tue, 20 May 2008 08:29:00 +0000

A SCADA system performs four functions:1. Data acquisition2. Networked data communication3. Data presentation4. ControlThese 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 SystemThe 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 AcquisitionFirst, 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 temperaturein 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 CommunicationIn 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 acentral 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[...]

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

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 ar[...]

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