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temperature sensor network

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embeddedfactory

Electrical
Nov 23, 2004
2
Hi: I am new to the forum, I am Alejandro from Argentina. I was asked to build a low cost temperature sensor network.
The network will have 10 sensors separated 10 meters each.

I would like to hear your opinion about the technology to use, I know that 4-20 mA sensors are suitable but very expensive, 1-wire sensors can be an option.

Do you know any other low cost solution?.

Thank you in advance,
alejandro
 
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Hi Alejandro,

One of the cheapest sensors you can use is a thermistor with a negative temperature constant (NTC). They are small, they are cheap (a dollar apiece - or less), and they are non-linear.

They can be linearized with a series/parallel resistor over a limited temperature range (say -20 to +30 degrees, or 0 to 50 degrees) if you need that. If you evaluate the temperature with a computer, you can linearize in the computer program and the temperature range can then be more than 100 degrees celsius.

Google "NTC thermistor" for tons of more information.
 
Thank you very much for your help.

I do understand that NTC can be a cheap solution.

I was wondering how can I reach a CPU (for instance, a PLC) with that information (the measured temperature). That is to say, how can I "send" that temperature to a PLC that is 10 meters away from the sensor.

That is why I was considering 4-20mA and Dallas' 1-wire as options.

Best Regards,
Alejandro
 
Use the Barix BarioNet controller ( with the Dallas 1-wire sensors. With a small extension module, the controller can connect to as many as 16 of these sensors for something like $400 total. The controller can log data locally, display dynamic values on its built-in webserver, send data to a server, etc...
 
This is not to promote a given product - I have not used this equipment. Acromag makes a din mount module that takes 24 VDC for power and you can communicate with it with ethernet, modbus RTU, or other medium/protocol. Just find one your PLC supports. The RTU unit can be found at
 
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