S7 300 Series CPU - funny crash.

RMA

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Sep 2004
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While testing my program, which is the subject of another thread, the CPU crashed twice for no apparent reason. All the LEDs except for BF were blinking and the only way out was to power down and back up. Trying to do a memory reset with the Start/Stop switch didn't work.

Anybody ever seen anything like it, or have any idea what might have caused it?
 
Roy

I have never experienced the fault that you describe..

but, here's a shot in the dark..

I am wondering if, maybe, a MMC card fault caused this problem. :confused:

Just a thought.

Paul
 
Hi Paul,
If the CPU is one of the newer generation equiped with MMC then you could be on the right track. I've experienced some strange activity with the CPU status LED's and in both times - Replacing the MMC cures the Problem. If you send them back,siemens will replace them for you if found defective.

Steve
 
Stevo

I suggested the MMC card to Roy mainly because he is using the 'newer generation' CPU's that come with MMC cards.

It's nice to know someone else is thinking along the same lines as me. :unsure:

Paul
 
Since I was more concerned with my program problems, it didn't occur to me to check the the fault buffer. If it happens again, I'll have a look and post the results.

You might be right with the MMC though, Paul. I get the impression that these new generation MMCs are not 100% Bug free. The first one I got was faulty straight out of the box and the way the hot line and returns dept. reacted, the problem was obviously VERY well known!
 
It's just crashed again on me today, as I was downloading the full projekt complete with (more or less, see another thread) working program for the FM352-5s.

After it crashed, there was no communication to the CPU. After powering off and back on, I had a look in the CPU diagnostics buffer. It was stuffed full with endless read/write faults culminating in a message "DEFEKT:Internal System fault"
On the next line was "Invalid module: change of module and memory reset necessary"
And on the next line was the "Power On, buffered" message, as it came back up.

Any thoughts?
 
Roy, I can think of a couple of possibilities:

1. I had spontaneous crashes on one particular CPU before. It would go to stop mode and all lights would flash. I couldn't go online, and the only way to get the machine running was to download the program again over MPI. The difference though in my case was that there were no diagnostic entries (I guess those were blown away too), so I don't think it is the same thing. It ended up being caused by noise or voltage coming in on a modem that was connected to MPI, and once I disconnected it, I had no more problems.

2. When you download the new project, do you put the CPU in stop mode? If not, it's possible that as the blocks are downloaded, one of them might not be compatible with some of the older blocks, especially if your DBs are initialized in the startup OBs. Perhaps this caused your R/W faults.
 
S7Guy said:

2. When you download the new project, do you put the CPU in stop mode? If not, it's possible that as the blocks are downloaded, one of them might not be compatible with some of the older blocks, especially if your DBs are initialized in the startup OBs. Perhaps this caused your R/W faults.

That's a possibility I hadn't considered. I don't usually bother to stop the program before downloading and that might explain why it only happens occasionally (possibly after a big modification). However, thinking about it, I'm fairly sure the last couple of times, it happened while I was testing the program, not while downloading, but I'm not 100% sure. I'm running both the MPI for the PC and the DP interface for the module connection at 1.5 MB, so when your viewing something (plus a VAT being updated), especially in S7-Graph, there's a lot of comms load going on.
 

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