This kit is a PC Based 4 channel temperature logger and display (deg C or F) using the serial port, a PIC12C509 and 4 x DS18S20. No external power required. We think that each DS18S20 may be located over 200 meters away from the motherboard and PC.This is an 8-pin micro-controller based circuit for temperature data logging via the serial port of any computer between 1 and 4 remote digital temperature sensors, DS18S20 made by Dallas. The output data is a continuous stream in simple text format (sensor number followed by temperature reading to 2 decimal places). Simply capture the data to a text file and then import it into Excel to produce tables and charts of temperature readings over time.
The users can tailor the input data stream to suit their purpose - it may be dumped into an Excel spreadsheet, or they can write BASIC programs using the INPUT command to grab the readings. As you can see from the pictures there is not much to the hardware (the PCB is just 45x45mm) and most of the work is done by the PIC.
Provides real-time data via the serial port, by interfacing with up to 4 DS18S20 Dallas temperature sensors. It has an accuracy of 0.5 degrees centigrade. You must choose either Fahrenheit or celcius based on a jumper. There is no external power required for this kit, because it gets its power from the serial port. The data stream is easily logged & processed. You can run each sensor over 200m distance from the board. We have provided one DS18S20 in this kit. This allows you to test the kit. If you need more sensors, you can buy them here. We also have not provide cables to connect between the kit and each remote sensor. But we do provide a harness and connector for easy connection of the cables to the PCB. We have not tested the maximum distance which the sensors can be located from the PCB but believe it to be much more than 200 meters/yards.
First check the components supplied against the Component Listing. Follow the overlay on the PCB to assemble the kit. If you want to measure degrees Fahrenheit then add the Link 'F' to the board where shown. The default measurement is in degrees Centigrade, or you can add the Link at the 'C' position. The pin-out of the DS18S20 is shown here. You can easily determine how to connect the sensor to the 3-wire harness by looking at the back of the PCB to see which is the ground connection. No external power is required. The kit is powered from the serial port of any type of computer.
There are several ways to read the temperature data. You have to use a terminal program set to 2400 baud, 8 bits, no parity, 1 or 2 stop bits. The easiest way is to use Hyperterminal. Use the capture to log or save data. You can write your own program in BASIC using the INPUT command to capture the data as it comes in.
We believe the sensors may be located more than 200 yards from the PCB. Just check that the remote VDD is above 4.4 Volts. The kit designer recommends 10uF tantalum capacitors be placed across the power supply pins (not supplied) to minimise random errors and possibly get increased range. If power supply from your serial port is a problem you could use a lower current drawing 5 voltage regulator.
The DS18S20 has an operating temperature range of -55°C to +125°C and is accurate to ±0.5°C over the range of -10°C to +85°C. The sensors can be mounted up to 200metres away from the logger. Data is read out over a 1-Wire® serial bus in 2's complement format with 9 bits of resolution. The DS18S20 offers thermostatic functionality with over-temperature (TH) and under-temperature (TL) user-programmable setpoints stored in on-chip EEPROM. An internal flag is set when the measured temperature is greater than TH or less than TL. If thermostatic operation is not required, the two bytes of EEPROM reserved for TH and TL may be used for general-purpose nonvolatile storage. Each DS18S20 features a unique and unchangeable 64-bit silicon serial number, which serves as the bus address for the sensor. This allows multiple DS18S20 devices to coexist on the same 1-Wire bus. The DS18S20 may be locally powered via a 3.0V to 5.5V supply, or power can be derived from the 1-Wire data line ("parasite power").
KEY FEATURES±0.5°C accuracy from -10°C to +85°C
Measures temperatures from -55°C to +125°C (-67°F to +257°F)
9-bit (expandable) resolution
1-Wire interface requires only one port pin for communication
64-bit unique and unchangeable electronic serial number
Multi-drop capability for simplified distributed temperature sensing
Alarm function with user-defined nonvolatile alarm settings
No external components required to measure temperature
3.0V to 5.5V supply range
Optional "parasite-power" operation (power derived directly from 1-Wire bus)
TO-92 (DS18S20) and 150mil 8-pin SO (DS18S20Z) packages Thermostatic Controls
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