1747-sn FAULT

[Etech883]

hello I am getting a 57h fault - Specialty I/O module has not responded to a lock shared memory command within the required limit. Fault randomly happens and can reset and run fine again but keeps coming back. we have swapped the scanner card already and still happening. I found a old print to see what it was all connected too and looks like (3) 1791 I/O (2) 1771 PLC and a PV600. The scanner card is in a 1746. So far I haven't found all the devices in the shop yet I have found (2) 1791 and (1) 1771 and the pv600 they all seem fine with no faults. Does anyone have some suggestions? have already checked connections on what ive found so far.

 

[Ken Roach]

Thanks for those details !

Because it's a backplane communication fault, the problem probably isn't on the RIO network or with any of the RIO devices.

And because the problem persisted when you replaced the 1747-SN RIO Scanner, then the root issue is probably a failing backplane or power supply.

There is a narrow possibility of mis-addressed Block Transfer buffers causing that xx57h fault if the same buffers are used in more than one block transfer function. But the Knowledgebase actually specifies that cause for the redundant 1747-BSN, not the normal -SN. And if the program has not been changed recently that's an unlikely cause.

If you have an available slot in the chassis with the SLC-500 CPU, you could try moving the 1747-SN and re-addressing all the logic related to that slot.

 

[Etech883]

Thank you for the reply! I do not believe anything has changed in the program.

I had talked with a Allen Bradley tech connect and he did tell me that certain dates of backplane are know for issues but I was unable to find a date on mine to confirm it.

He also told me to check my grounds and they seemed fine but this system goes though a shop that's 1/4 mile long lol and some things were unhooked and have know idea of location to even check.

I think we will move forward with a new backplane.