Has anyone found that some comms issues occur when online with PLC ?

[PhilPike]

At our facility we have some strange behavior from one of our ControlLogix PLCs. It runs three palletizers. We have had some rare but very disruptive communication issues, and almost exclusively when someone is online with the PLC. Otherwise, we cannot explain it. So right now it's more of a hunch than anything.

Has anyone heard of this being a possible cause of problems? If two users are online with the PLC using Studio5000, and possible running some Trends, can this possibly affect the PLC's ability to run code and communicate with other devices reliably?

It is a 1756-L72S GuardLogix 5570.. rev 28.. System Overhead Slice is 30% right now (and set to Run Continuous Task during unused time slice). Data & logic Memory is at less than 50% usage. MainTask is running max 18ms scantime, max 18ms interval time.

TIA !

 

[dmroeder]

Duplicate addresses certainly can be catastrophic.

Your ControlLogix ethernet module has a built in web page, it has some very useful statistics. I would look at it to find out how it is performing.

 

[JeremyM]

How much Class 1 and Class 3 stuff is happening?

 

[James Mcquade]

as already suggested, duplicate ip addresses.
and also
if one pc s linked to the plc via hard wire connection AND its wifi is on.
and pc #2 is linked to the plc via wifi and is connected to the plant via ethernet cable.
if both pc's are linked to each other, THEN you can have a network loop issue n which the plc has a circular loop back to itself through the pc's. i'm not sure i am explaining it correctly, but it will kill the communications to other devices.
i discovered a bug in an access port when that happened, the access point company said it could not happen. i nearly shut down the entire plant.
i had to reprogram the access point offline to correct the issue.
regards,
james