S5 115U Intermittent stop - STOANZ

Hi Guys,

Working with an S5 115U PLC, getting a lot of PLC Stops randomly. See attached photos for iStack info.

I am trying to work out what is causing the stop, any help would be appreciated.

I see that STOANZ indicates an internal stop request, so I assume this is a STP instruction, could it also be from an STS instruction?

Currently get a STOANZ fault on the iStack info and it indicates the areas of the program below.

The weird thing is if we get a PLC stop, flicking the PLC switch from run to stop and back does nothing, but if we power cycle the power supply to the remote IO rack and then try it works. The power supply has been swapped with another and the issue persists. Any ideas on what to look for?

[snip] ...

Hello Matt_b,

we need another screenshot, from Interrupt Stack Display (see attachment).

But please in better quality.

Hi,

I could not access the next page, I tried using F7 but everytime it give error 0334. Is there any other way to locate the fault?

The image resolution was dropped reduced automatically, i uploaded with original size, perhaps it was too large, I will try and re-upload

No, you must know, at which address and in which block the CPU goes to STOP.

For error 0334:

"System message no. 0334" when attempting to go online with STEP 5 V7.2 in Windows XP