Active 4-20 output to and Active input

[Jason P]

Hi there,
I have a 4-20mA signal duplicator that has 2 active 4-20mA signals. Unfortunately my PLC input card is also active. If I reverse the voltage polarity on the card power will that effectively cancel the voltage? +24V and -24V or will this cause problems long term? It works when I do this but the theory behind it I'm not sure is correct.

 

[OkiePC]

Tell us what PLC hardware and signal conditioner you're using.

 

[Firejo]

THAT'S FUNNY!!!

 

[danw]

How do you ‘reverse the voltage polarity on the card power”?

Doesn’t the AI card derive its power from the backplane?

Does removing the power disable the entire card or just the loop power?