Sign in to follow this  
Followers 0
Arun Opto 22

Why "RMS" Analog Input?

6 posts in this topic

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

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

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

Arun

Share this post


Link to post
Share on other sites

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.

1 person likes this

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0