Fault question

fatd132

Member
Join Date
Nov 2014
Location
louisiana
Posts
4
Hello,
I got an alarm - "Specialty I/O module in slot 4 has not responded to a lock shared memory command within the required time limit" - my first thought is to change out the card and see what happens. I have ordered the card and waiting till it arrives. If I clear the alarm the plant will run for a few hours then faults again. Is there any other ideas I should try?

Thanks

plc problem ntp.jpg
 
so, let me guess from your vague post 🔨

..............RSLogix500.

Is it an SLC?
Is it a Micrologix PLC?

What is the specialty module?
What is connected to the module?
Does it have power?

What other I/O modules are connected and are they all working?
Can you remove said I/O modules and leave only the "faulty" one to test it?
 
Could be the I/O module needs replaced...but you need a spare for that....

Is there a problem with the power supply, you could replace the power supply if you have a spare.

Also, check for bad grounding. Noise could be entering the backplane and messing with processor comms to the I/O. Specialty modules are more complex, so more sensitive to this issue.
 
What is the IO module in slot 4?
A specialty module generally includes things like the Basic Module, or some other module that has an onboard processor and communicates to the main processor with M files, and require programming or configuration of their own.
 

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