allen bradley SLC 500/2

[aebrahim 0]

I have slc 5/02 i found all outputs are energized at same time (i have tow digital output card type OB16) without any change of input and when i made reset by external pushbutton all output become normal again any help for this issue Edited 27 Dec 2011 by aebrahim

[Mickey 71]

Are the outputs in a conditional subroutine? Forces? "MCR" instruction? "Jump" instruction? What did you do to reset? SLC500/2 ? Do you mean SLC5/02? Can you post your .RSS file? Someone can help you look. Edited 26 Dec 2011 by Mickey

[Ken Roach 194]

I agree that to diagnose a programming problem that you should post your *.RSS file. The default behavior of Output points is to turn OFF in the event of a user program fault or operating system fault. If all of the Output points of a controller turn on simultaneously, I suspect a user program issue that causes data to be written to the output image table incorrectly.

[aebrahim 0]

thanks for your attention first i have reset push button on the front of the panel so when i pushed this buttn this make reset for all output second yes i mean SLC 5/02 finally i attached the .RSS file thanks BTG .RSS

[aebrahim 0]

thanks for your attention I have reset push button on the front of the panel so when i pushed this buttn this make reset for all output I attached the .RSS file thanks

[aebrahim 0]

BTG .RSS

[nehpets 19]

Welcome to the forum, I would suggest that the 'lamptest' pushbutton is wired incorrectly it is probably wired normally closed instead of normally open, this would be indicated by input I:2.0/5 being on (active) when the pushbutton is not pressed. Steve

[aebrahim 0]

thanks this machine worked sinc 2001 and not indication lamp only energized but all outputs are energized thanks again

[Ken Roach 194]

Is the "Reset" pushbutton on the front of the panel wired to Input I:2/4 "Alarm Reset", or does it do something else like reset power to the controller ? Please confirm that ALL of the outputs on both output modules in Slot 3 and Slot 4 are turning on. Are the output LEDs on the Output modules turning on, or is voltage just appearing at the terminals ? Several of the Outputs are not commanded by ladder logic at all (the last 8 of Slot 4, and bits 4 and 5 of Slot 3) and therefore they could not be set or reset by ladder logic. If an HMI device or MSG from another controller (unlikely, as only Node 0 and 1 show in the Active Nodes table) is writing to the output table, the outputs that are commanded by ladder logic would not change state. I cannot see a reason in the program for all of the Outputs to turn on; there is no indexed or indirect addressing, or Copying of data to the Output table. The fault behavior of all SLC controllers is to turn the Outputs off. I am interested to learn what the "Reset" pushbutton really does, and whether it was added to deal with this issue or has been part of the system from the beginning.

[rswolff 9]

worked correctly but I'd still fire you....when I taught plc (2 semesters) I had one rule....if you used a latch (or unlatch) instruction you would automatically fail. I would look at Filter2 or possibly some other latch thats on (when you don't think it should be)....and resynchronizes when you press the button.... I'll run it over weekend and know for sure....

[aebrahim 0]

Alarm Reset pushbutton make reset for alarms only ,because alarms are latched. I was'nt not there when the problem accured but operation guy told me all alarms on and all pumps running Reset bushbutton has been part of the system from the beginning

[OkiePC 14]

That is not quite the same as all outputs are on. Are you able to verify this yourself, or are you only able to trust what "operation guy" told you? I have never seen any A/B PLC turn on all local outputs unless programmed to do so, but I have seen (once) a remote I/O device do that very thing. Without knowing the electrical circuit and knowing the system, it is difficult to suggest your next step. Paul Edited 31 Dec 2011 by OkiePC