PLC Outputs Passing through ESD Contacts.

H

Thread Starter

HSN

Most of my experience has been that PLC Output(s) are de-energized during an ESD condition even though these outputs pass through ESD contacts. I've seen this type of application many times and I assumed this is for redundancy; hardwired ESD contacts are a last line of defense in case the PLC output card fails.

On the other-hand I've been told that this adds confusion because the PLC is not doing the ESD logic. It’s simply uses the ESD feedback status as an interlock condition within the PLC code to de-energize the PLC output. Thus since the ESD logic is done externally it shouldn't be added as an interlock condition to the PLC output.

Should the ESD Status be added as an interlock to de-energize PLC output(s) if the PLC output(s) pass through ESD contact?
 
B

bob peterson

I do it this way just so I know that the PLC output goes off when some
external event happens.

--
Bob
 
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