Incorrect programm execution S7 314 1

[AndyAm]

Hello,

I have a project running in a S7 314 plc. The plc is a recent type with 64kb ram, and a 128kb micro memory card.
The 57kb of the ram memory is used. My problem is that some of the S7 timers are not always working correct. When I have cleared the plc (deleting all bloks online) and then download the whole project, the timers are working correct, but after some time (a couple of hours) their output remains high althoug the input is low (ondelay timers). It seem to be always the same one or two timers. When I replace them by other timer numbers, the new timers work ok for a couple of hours but afterwards they are again constantly high. I'm sure that the timers are not used at another place. The timers are called in a function that is called in OB1. One time, powering the plc on and off seemed to temporarely fix the problem, after a couple of hours the same problem occured. When I retried the procedure with powering on-off, it didn't help anymore. Yesterday, I cleared the plc once again, downloaded the whole programm, but the timers remained high from the beginning??? The timers are activated in a rather complex network (programmed in FBD), could that be a reason?
Besides this problem, what is the correct procedure for clearing a S7 300 plc with MMC, it seems when deleting all blocks online, that the hardware configuration is still present (system time remains correct after clearing??)?

Thanks, Andy

 

[Macbeth]

As you stated at the end of your post, a complex nesting can cause the problem you are seeing. I beleve in reports there is a program structure report. This program structure has numbers at the end like "(147)" if this numder exceeds 255 then you are right. You must decrease your nesting below 255

 

[AndyAm]

Thanks Macbeth,

Your explanation could be the reason for the incorrect execution. But in Step7 v5.3 I cannot find a menu for 'programm structure report'. How can I create this 'programm structure report'?

Thanks, Andy

 

[Rheinhardt]

Hi AndyAM,

I doubt it very much that you would exceed the maximum amount on the call structure.

255 is alot,

You can look at your call structure by clicking Call structure TAB at bottom of where you would typically find your LAD instructions,then analyze this.

Can you maybe post your code or a similar attachment.

If i understand right you want to trigger the reset but the value remains high, are u using the timer the right way, triggering a reset.

Which timer are u using spesifically On delay, retentitive on delay with paramters??

Would certainly help if you explain a bit more

Regards

Rheinhardt





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