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Topic: Reading a thermocouple ? (Read 604 times) previous topic - next topic

Gadget999

I want to read a thermocouple/pyrometer

i have one of these lying about so can use it

http://www.morshine.com.tw/upload_pdf_c/257.pdf

how do i wire it up ???

what else can i use to read thermocouples

Grumpy_Mike

Well first off that is not a thermocouple.
Second it is a very poor data sheet, in fact it is not a data sheet at all. There are 5 connections and it doesn't tell you what any of the connections are. So there is not enough information in the sheet to answer your question.

Try contacting them and asking for a real data sheet not a specifications sheet.

Gadget999

They were not 100% helpful

I managed to find this

http://www.s-products.com/site/specifications/RT82000.pdf

it has an output of 4-20 ma ?

am i right to assume it will work as a variable resistor ?

there are 5 pins

1 +12V
2 gnd

3 - tc
4 + tc
5 no markings


pwillard

4-20 mA is not a variable resistor... it is called "current loop" communication and it still remains popular for industrial sensor interfacing.

It's been discussed before... have a look here:  http://arduino.cc/forum/index.php/topic,19613.0.html

retrolefty


4-20 mA is not a variable resistor... it is called "current loop" communication and it still remains popular for industrial sensor interfacing.

It's been discussed before... have a look here:  http://arduino.cc/forum/index.php/topic,19613.0.html


Well in fact a 2 wire 4-20ma industrial 'transmitter' does indeed act just like a variable resistor. You power the 'current loop' with a typical +24vdc power supply and the 'transmitter' automatically adjusts it's output resistance to maintain the loop current at a specific value corresponding to it's measurement value within it's 4-20ma measurement output range. A typical way to measure the loop value is to wire a 250 ohm resistor at the 'receiving end' wired in series with the ground end of the loop power supply and it will drop a value of between 1-5vdc across the resistor suitable for measurement by a typical analog input pin.

Lefty

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