Hi guys,
the German's beat you to it this time. For the benefit of anybody else with this problem in future, the problem was that I was trying to go in from the offline copy of the program. You have to switch to online mode in Simatic Manager and then open the online version of the program - as usual it's the little things that cause the problems!
However, I'm still only halfway there. I can set by breakpoint OK, but I don't seem to be able to observe the program "dynamically" so to speak. One consequence of that is that I don't know whether or not the program has reached the breakpoint.
Is it possible to observe the running program online, or do I have to set (extra) Merker at different places in the program and then observe these in a VAT?
I set up the conditions that should have caused the program to run up to the breakpoint, but in the VAT some Merker which I would have expected to be set weren't. That could, of course, have something to do with the fault I'm chasing - or there again, maybe not, since I don't know whether the program hit the breakpoint or not.
A thought just occurred to me, if the program hits the breakpoint effectively it has stopped running. Do the CPU LEDs go to STOP in this case?
TIA
Roy
PS Another thing I noticed, was that all the Blocks from the main program are still visible online, although I loaded a very cut-down version of the program. It's a slightly worrying thought that under some fault conditions you might suddenly start executing code that you didn't even think existed. Is this a real possibility? I think I might take to deleting the MMC in future, just to be on the safe side!