analog differential or single ended inputs
analog differential or single ended inputs
(OP)
I am wiring four 4-20 mA inputs to a control logix 1759 AI8 module, via IFM module. All four inputs are from 4 wire transmitters, supplying their own power. I have two options,
1. Wire the card as differential analog inputs giving me no spare inputs.
2. Wire the card as single ended inputs, giving me 50% spare capacity.
I am leaning towards option 2, my uncertainty is having the commons all tied together (single ended input). Is this a problem if all the 4-20 transmitters are isolated? I think not but am a little unsure. Thank's for any response. Steve
1. Wire the card as differential analog inputs giving me no spare inputs.
2. Wire the card as single ended inputs, giving me 50% spare capacity.
I am leaning towards option 2, my uncertainty is having the commons all tied together (single ended input). Is this a problem if all the 4-20 transmitters are isolated? I think not but am a little unsure. Thank's for any response. Steve





RE: analog differential or single ended inputs
If yes. I'd go with single ended. Just don't do anything that would prevent you from going to double ended if some hitch comes up.
With your isolated 4-20 I think you're good.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: analog differential or single ended inputs
What you describe seems to be exactly such a system, so just do it.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: analog differential or single ended inputs
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: analog differential or single ended inputs
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: analog differential or single ended inputs
The analog current input card has internal 249ohm resisors, so the card does the conversion to 1-5 Volts.
Steve
RE: analog differential or single ended inputs
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com