4-20 mA signals

fishenguy

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• Dec 10, 2010

• #1

I need to run a 4-20mA signal from a Pro-face PLC to a AB Plc. The distance will be about 600ft. I plan on using 18 gauge shielded cable. Is this possible? What other suggestions would you have.

Thanks, Dave

 

Mickey

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• Dec 10, 2010

• #2

Yes, use shielded cable ( connect shield on one end to ground).

 

fishenguy

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• Dec 10, 2010

• #3

Thanks for your help again Mickey.

Dave

 

rguimond

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• Dec 10, 2010

• #4

If you can read via MSG command from AB PLC over a physical network (Modbus. RS-485, Ethernet, etc.), I would use that method. One cable could take the place of several shielded analog cables if you ever want to expand the capabilities of the network in the future

 

Tom Jenkins

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• Dec 11, 2010

• #5

One thing to watch for is grounding. Running analog I/O from one controller to another you mught end up with the "-" tied to ground on both controllers. This can be worked around, but you need to watch for it.

 

OkiePC

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• Dec 11, 2010

• #6

I normally power up the signal source with a load before landing the other end to check the voltage differential to the receiver's common and ground. If that potential exceeds the specs for the card(s) or it's not described in the book as isolated, just add an isolator (signal conditioner).