Vxxx-RA22 mV measure potential

[Lemur]

Hi,

thinking about possibility of using a thermocouple input of RA22 controller to measure a voltage across a shunt resisitor - to measure the DC current. Haven't found any information if the input must be floating, or can be tied to a potential of DC source.

 

Thanks n regards

Lemur

[Joe Tauser]

Shunt voltage is a special case because it almost never has the same common as dc ground, unless it happens to the the last thing in the circuit.

 

Every time I've done this I use a DC/DC isolator an just output a regular 4/20 signal to an analog input.

 

Joe T.