logix5561 online ladder modification

ahmed megahed · Oct 20, 2011

Dears
I was making online modification in such CPU when i was in remote program mode starting to edit rungs as per manual
edit rung
modifiy
accept the rung

but i found that after this step the controller fix some output without any change as ex. keep the valve open and not excuting program to close knowing that the block which i was modifing has no relation with this output which is freezed to open

is any one has experience with such situation and why it happened

thanks in advance

bornwild · Oct 20, 2011

I didn't understand what you wrote. Can you rephrase it

ahmed megahed · Oct 20, 2011

here it again
i was making online modification for some rungs, the steps was:
i went to remote program ( run led was off)
edit the rung
accept the rung
but what happen is when the new rung is going to be excuted i found that one (input) from the rung which i edited is going to one and freezed this is what i noticed may be many gone to freeze
is there is a reason for this ?

i hope it is clear

MarkNightingale · Oct 20, 2011

Just a quick check - did you put the key switch back into run mode?

And did you accept all the rung edits and then assemble them?

Mark

ahmed megahed · Oct 20, 2011

actualy i start modification by REMOTE program mode
and i was going to edit one rung
after edit
accept pending rung edit
then no need to assemble because i was in program mode not run mode
before returning the mode to run this problem happened

MarkNightingale · Oct 20, 2011

Can you post your code? and outline the rung you changed?

nightline · Oct 20, 2011

As far as I know, and I only do is programming online or offline, never in remote program.

MarkNightingale · Oct 20, 2011

When you do edits online you have to accept the pending edits, this then tests the edits but does not execute the edits.

Then you have to test the accepted edits, which means the program is now running those edits.

Then finally you assemble the edits.

If you edit in program mode then you have to put the program back into run mode.

Mark

nightline · Oct 20, 2011

MarkNightingale said:
When you do edits online you have to accept the pending edits, this then tests the edits but does not execute the edits.

Then you have to test the accepted edits, which means the program is now running those edits.

Then finally you assemble the edits.

If you edit in program mode then you have to put the program back into run mode.

Mark

In which version of RSLogix5000 are you working?
I'm working in V19 and can edit directly with one button...

ahmed megahed · Oct 21, 2011

Dears
My version is V16 and i make many modification before with the same mode remote program
and sure after excuting the modification i have to return back to run mode but this problem happened before going back to run mode
and after i edited i did accept the edit rung and this step include also the rung verification.
sure the rung which i did is corrct brcause i left it in the programe after this problem without any problem

DamianInRochester · Oct 21, 2011

ahmed megahed said:
actualy i start modification by REMOTE program mode
and i was going to edit one rung
after edit
accept pending rung edit
then no need to assemble because i was in program mode not run mode
before returning the mode to run this problem happened

On a side note, I really caution against your approach on this. Since you are working only "online" I assume that you don't have a commented version of the program. If this is so it is very important to upload the progam and state of the controller, and back it up to a separate file name before making any changes.

It sounds to me that the last guy may have had forces enabled, and what you did lost those forces.

ahmed megahed · Oct 21, 2011

there was no forces in PLC before downloading
but is there is any way PLC will go freeze in any case

Ron Beaufort · Oct 21, 2011

I'd be willing to bet (much more than pocket change) that what you saw was actually the RSLogix5000 software "freezing" instead of the PLC ...

it's a fairly common occurrence to have the software do weird things – as shown in the picture below ... this was something that happened to a student in one of my classes a few months ago – and I was able to capture a screen shot of it ... we had to stop and then restart the software to clear up the problem – and the same situation has never happened again ... this was version 16 of the RSLogix5000 software ...

notice that the CTU and the CTD instructions both have exactly the same address ... that means that there is only one Accumulator involved ... so theoretically the value shown for the Accumulator in the CTU instruction should always match the value shown for the Accumulator in the CTD – and it should also match the value shown for the Accumulator being shown in the Tag Listing ... obviously that didn't happen ...

going further ...

as the input switch (bit 2) controlling the CTU was toggled OFF and ON, the Accumulator value shown in the CTU instruction stayed "frozen" at ZERO - and it would not count up ... at the same time, the Accumulator shown in the CTD instruction did indeed "count" – but it was actually counting UP instead of DOWN ...

note that the value for the Accumulator as shown in the Tag Listing did indeed accurately increment upward each time the switch for the CTU instruction (bit 2) was toggled ON ...

to the student, it looked like the input switch was controlling the wrong "counter" – and that the CTD instruction was "counting Up instead of DOWN" ...

but ...

when you get right down to the key facts, the value displayed for the Accumulator in the CTU instruction stayed "frozen" and would not update on the screen ... everything else was actually working correctly ...

in other words, the PLC was NOT "frozen" in any way - it was only the SOFTWARE that was hung up and not displaying the PLC's status correctly ...

we finally had to stop and then restart the software in order to clear up the display problem ...

so ...

as I said earlier, I'll bet that the problem that you saw was actually the RSLogix5000 software display "freezing" – instead of the PLC ... if it happens again, try to capture a screen shot of what you're seeing ... that might help us nail down your problem ...

.

logix5561 online ladder modification

ahmed megahed

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ahmed megahed

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