adccommunitymod (AutomationDirect) asked a question.
Created Date: June 07,2005
Created By: MikeS
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We have noticed the following behavior on the 260 CPU: when a STRPD of a stage is used in that stage and the stage is active while the PLC is written to, the STRPD action is exectuted again. When sequencing through a series of stages, this can cause havoc to the sequence with multiple stages active at the same time. This program was used on a 450CPU with older firmware and this was not an issue. Is this behaving as intended? If so, we need to change to latched coils for interlocking so the STRPD does not execute multiple times. Thanks for any responses.
Created Date: June 07,2005
Created by: MikeS
We have noticed the following behavior on the 260 CPU: when a STRPD of a stage is used in that stage and the stage is active while the PLC is written to, the STRPD action is exectuted again.
When sequencing through a series of stages, this can cause havoc to the sequence with multiple stages active at the same time.
This program was used on a 450CPU with older firmware and this was not an issue.
Is this behaving as intended? If so, we need to change to latched coils for interlocking so the STRPD does not execute multiple times.
Thanks for any responses.
Created Date: June 08,2005
Created by: franji1
Show us an example of the situation, in mnemonics, so we can better understand
Created Date: June 09,2005
Created by: MikeS
Example program:
ISG S0
STR SP0
SET S4
SG S4
STRPD S4
SET S10
STR C1
RST S10
END
Put the PLC in run mode so S4 is active, which sets S10 active.
Toggle C1 on and off to reset S10.
Make any edit, such as inserting a NOP rung, then write to the PLC.
S10 is now active again, even though S4 was already on and should not have seen a PD condition to set S10.
Is that supposed to happen? Any suggestions?
Created Date: June 09,2005
Created by: franji1
Your code looks good.
I would think that if you are doing a runtime edit, it should behave as you desire. However, if you are doing program mode edits, then switching to RUN mode, the current behavior is probably correct because the PD contact instruction states probably reset when switching between program and run modes.
Created Date: June 09,2005
Created by: MikeS
Yes, this is on a runtime program write.
Created Date: June 09,2005
Created by: franji1
Hmmm. I'm going to have to defer to the ADC engineers on this one.
Created Date: June 09,2005
Created by: Tech Guy
I don't have any other information at this time other than we are looking into it.
Created Date: June 29,2005
Created by: MikeS
Any updates on this yet?
I tested this on a new 450CPU with V3.00 firmware and it is still a problem on runtime program writes.