Re: [foxboro] system error in sequences
- From: Maks Wilde <mwilde@xxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Tue, 31 Aug 2010 09:53:12 -0400
Dirk & Others,
I strongly recommend a review of B0400DF (HLBL User Guide) when writing
standard exception handling subroutines. More specifically the "Useful Hints
on SBX Programming" section. The document even provides sample code on how
to correctly implement the SBX code and offers many hints as to do's and
don'ts.
It is also advisable to limit the number of SBXs (eg: TO_SYS_ERR,
TO_USR_ERR, TO_MANUAL, TO_INACTIVE, TO_PAUSED). If the sequence is executing
code in one of these SBXs, and another exception is caused, eg: block placed
to manual by user, your CP can REBOOT with a memory violation. I have seen
this at a site, and have replicated it on a testbed.
One of the documents advises not to use statements with multiple C:B.P
references. Instead you could have two variables (or just one) and do
something like this:
var1 := C:B.P1;
var2 := C:B.P2;
IF (var1 < var2) THEN .........
Hope this helps,
Maks Wilde
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