Calibrate thermistor and collect data

[nlaham]

Hi Guys,

I am working on a project and am not that electrically savvy so I was hoping if someone could let me know how I'm doing.

I want to use analog temperature probes (10K thermistors) and record data to a input module, which will convert it to Modbus (a communication protocol) that I can use for remote data aquisition.

These are the senors I would like to use - http://www.datanab.com/sensors/Thermistor_SSP3.htm

This is the input signal to Modbus converter that will accept the thermistors - http://www.obvius.com/pdfs/A8332-8F2D_Datasheet.pdf [Broken]

As far as I know, as long as I can read the data, I should be able to use the Ohm conversion chart on the datanab.com website to convert to Temp.

My main question is, if I change wire lengths, won't my resistance change. So I will need to calibrate each sensor based on wire lengths. Any suggestions on the best way to do this? I was going to use an ice bath, and a tea kettle boiler to calibrate at 0 and 100 degrees C.

Anyone have experience in this matter? I'm not sure if I need to send power through those sensors or if the input module will do that. Sorry, kind of clueless on all of this.

Thanks,
Nick

 

[anorlunda]

My main question is, if I change wire lengths, won't my resistance change. So I will need to calibrate each sensor based on wire lengths.

The answer is no, provided that the wires are not too thin. For a single thermistor, even AWG 22 should be plenty thick enough.