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PLC DO interface to ABB DCS DI and vice versa 1

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180zip

Chemical
Jan 21, 2009
4
I need to control a solenoid currently connected to a PLC from an ABB DCS in a remote part of a plant. So the PLC and DCS would "share" control of the 24VDC Solenoid. Any ideas on the best way to do this without a gateway?
 
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Depends how you want them to share. You can use two dry contact relay outputs in parallel - either PLC or DCS can energize the solenoid.

Put the two contacts in series, either PLC or DCS can turn off solenoid.

Wire DCS output to PLC input and do whatever logic turns you on, accepting that if the PLC goes belly up, so does your control.

Vice versa with PLC output to DCS input.

 
So when you say gateway there is no communications link between the PLC and DCS?

If true, is there physical IO points between both system. Like dry contact relays wired between both system from the DCS to PLC?

If you have a dry contact wired from the DCS relay output and the contact wired to the PLC input, just program this input on the PLC to trigger the solenoid with a program change.

dpc seems more complicated and could possibly cause you problems. I believe mine is more accepted way of wiring between systems with relays when gateway communications do not exist.
 
Great your idea is much simplier. Q: what is dpc? are you referring to the gateway?
 
Who's on first?!

controlsdude repeated what dpc said but somehow it's a simpler hook up.
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Keith Cress
kcress -
 
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