Why "RMS" Analog Input?

[Arun Opto 22]

Some PLC analog input cards (4-20mA or 0-10V) are listed as "RMS". I know what RMS means in math. But in the context of an AI module...why would someone choose this? Or, stated another way, what benefit does it have (either for the PLC user or even for the PLC manufacturer)?

Thanks in advance,

Arun

[b_carlton]

I could see this for a discreet AC input or output module but I see no reason for an analog module. Do you have an example or a link to such cards?

[Arun Opto 22]

b_Carlton - Thanks for the reply. Here is a link to an example, SNAP-AIVRMS

Arun

[pcmccartney1]

Based on the link, it truly is a RMS module, the input can be 0-250VAC or VDC.  Don't confuse this with a 4-20mA or 0-10V analog input module.

[Arun Opto 22]

Yes pcmcartney1, I think you are right in that it has to do with measuring AC Voltage (because an average would be "zero"), so RMS is used. The voltage for 4-20mA and 0-10V is DC.

[NevergoldMel]

Just don't run AC through that analog card input.