Analog Active/Passive issue

Bullzi

Lifetime Supporting Member
Join Date
Jun 2012
Location
Colorado
Posts
1,530
Hi everyone,
I have a new (for me) situation with a new job I am working on.
I am using the output channel of a 1769-IF4FXOF2F card to send a 4-20mA speed signal to a VFD. The manual for the drive says that the analog input channel is sending the loop power out and should not be connected to an external supply. So in the Analog Input is a Active Input. The IF4FXOF2F is also a Active output. Neither of the 2 seem to have a jumper or switch that will change it from Active to Passive. So how do I interface these 2 together without frying something?

Is there anything on the market that will take a Active input and make it passive on the other side?

I would appreciate any help you can offer.
Thanks,
 
As per mickey's post, what you want is called a loop isolator.

What model of drive, that's quite an unusual feature? For it to be an active input with loop power supplied by the drive, the "negative" end of the input would be internally tied to the drive 24VDC power supply zero volt rail.

You may be able to make this work by wiring the analog output negative to this zero volt / common terminal. But I'd want to see the drive manual before recommending that.
 
Thanks Mickey and Saffa,
Loop Isolator, that is what I needed to know. The drive is a Phase Technologies APG series. It is a older drive that is no longer in production.

Looks like AutomationDirect.com has a Isolator (FC-11) that should do the job.
Thanks again!!
 

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