4-20mA output to datalogger

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4-20mA output to datalogger

Post by davetommo » Mon Sep 22, 2003 1:58 pm

I have a air flow transmitter that gives a 4 - 20mA output and I want to conect to a datalogger. Any suggestions on what type to purchase and how to configure it as all the ones I have seen on the site are voltage controlled. I spoke with tech support and they suggested using ADC-11 with a 120 ohm resistor which would convert 4 -20 mA into 0 - 2.5V. How do I configure the resistor.........feeling a bit thick at the moment :?
Anybody give me some advice?

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Post by markspencer » Tue Sep 23, 2003 7:39 am


The 4-20mA output from the sensor can be used with the ADC-11, so long as it is not a current loop.

To turn the output into a voltage that the ADC-11 can read 0-2.5 volts the 120 Ohm resistor is placed between the gnd and the input.

This means that your sensor will have a Ouput Signal (+) and gnd cable. If this is not the case the signal will have to be signal conditioned first to turn it into a single ended voltage. If you are unsure of the type of output from the sensor contact the manufacturer.

If you use the ADC-11 terminal board, this will make it simple to make the shunt resistor.

Best regards

Mark Spencer

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