Allen Bradley PLC's For controlling Pumps and other things

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Thread Starter

Walt Flannagan

We have recently installed an Allen Bradley Programmable Logic Controller in a rack with a power supply. Then we put in cards and pushed the dipswitches to the place were the manual specified per our application. The Allen Bradley is a PLC model 5/40 and we use DH for our remote I/O. Myself and another coworker did all of the programming and it controls pumps and level and temperature things. Upon initial startup everything worked really good, and upon review with the operators, we noted our changes. Well now everytime we sit down to program and I put the PLC in program mode, the PLC stops controlling. How can I control and program at the same time? Would it help if we upgraded the PC from Windows 98 to NT or even 2000? Thank you very much for any assistance.
 
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Steve Myres, PE

A-B PLC's have capability to accept "runtime edits", meaning that rungs can be added or altered while the PLC is running. When you choose to edit a rung in the programming software, the PLC makes an inactive copy of the rung and inserts it in the code following the original rung. You can then make your desired changes to this new but inactive rung. When you finish, you must accept the rung edits, and the software verifies the rung for syntax. Then you test the rung. On the next scan, the new rung begins to be executed, and the previous rung becomes inactive. If you are satisfied, you can make the change permanent, and the original rung is deleted. If the changes are still not right, you can reverse the test process, reverting to execution of the original rung, and continue to edit the new rung.

<b>BE VERY CAREFUL!!</b> On some A-B PLC's, deleting a rung while running will cause the PLC to crash. Also, you obviously need to carefully think through any changes you make as they will be executed immediately.

 
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Zan Von Flue

hi
I had a AB course and this was one of the negitives about AB. Online changing of a running program. The PLC has to be in stop to change the code.

later
zan

 
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Jocko Harmet

Gentlmen,

If you want to make changes on line, you can do so with the processor in run mode using the on line edit function.
In this mode, when you are on line, you can either use the Icons below editing tools or right click on the rung number.
see your programming manual or online help for details.
When you go offline or save the document you will be prompted to update your offline copy of the program.

Jocko Harmet
Tamtech, Inc.
Phoenix, AZ
[email protected]
623-580-1100
 
C
The PLC is designed to stop executing the logic when you put it in program mode. That is a safety mode so that your edits do not cause inadvertant control actions. Progam = Stop, Run = Go.

If you want to edit in Run mode, go ahead and do so. You will have click several more times to make your changes (verify, accept, test, assemble), but you will have the option to test your changes before assembling them. You can untest your changes if the results are undesireable.

Sorry, I am assuming you are using RSLogix5. A.I., 6200, and WintelligentLogic5 are before my time and I am not familiar with their on-line programming modes.

- Chip
 
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Do not put programmer in program mode. Put it in Run/Program (might be called remote/programe)mode. This can be done with software.
 
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Trevor Ousey

PLC5's, SLC5/03's,SLC5/04's,SLC5/05's, ControlLogix all have Online edit capabilities. The smaller SLC's don't and others may not.

IMHO Allen Bradley have done the online edits quite well, where you are able to test edits, then cancel or accept them depending on results.

Cheers.
 
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Walt Flannagan

Zan, now, an interesting sidenote, in the past I was an operator for in a swimwear plant, and on our tangerine line, I spefically recall watching the integrator change the program online without halting production. I did follow the advice of another individual who replied to my posting and we tested it on an old system with some ghosted code leftover and it worked. Thank you for your reply though.
 
THIS IS NOT CORRECT. YOU CAN MAKE CHANGES AND DELETE RUNGS, ALL WHILST IT IS RUNNING.

IT NEEDS TO BE IN RUN/PROGRAM MODE, NOT RUN, OR NOT PROGRAM.

IF YOU CHANGE TO PROGRAM IT WILL STOP AND ALL OUTPUTS WILL GO OFF.
 
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John Paley--Graphic Pkg Corp

Don't put it in program. You can edit, add or delete rungs on line with the keyswitch in the run/program position. rslogix (and A.I. for that matter) will allow online edits. In logix, right click on the left side of the rung and select start rung edits. a duplicate of the rung will be displayed and that's the one you edit. (I think it is identified with E's down the left side--if a rung is inserted, it is identified with I's)When you get the way you want, right click again and accept edits then test edits, then assemble edits. It' in there then. Limitations are--you can't create memory--if the t4 file max address is t4:10, you can'tuse t4:11 in an online edit. you can only create new memory space in the program mode. Be careful changes take effect now.
 
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Terry Howsham

You don't have to switch the PLC to "program" to change logic. Just go on-line using "Who Active", and then go to the rung you need to change. If you are using Rockwell (A-B) 6200 software, there will be a function button on the bottom of the screen to allow you to program on-line. If you are using Rockwell RS Logix5 software just double click in the area just left of the rung the start rung edits.
Don't forget !! once you have modified a rung, you must "test edits" and then "assemble edits"
 
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DAVCO Automation

Obviously you didn't either take a course on PLC 5's or you didn't learn anything, as has been said put the keyswitch in rem and in the software put the program in "remote run" mode and make online (running) changes.

Dave
 
We work on most A/B controllers and have for years. Most of us like to leave the key on the front of the controller in "REM" this will allow you to leave your processor in "RUN" mode and to perform online edits. The only thing that you will not be able to do is expand your data files. For that you must go to program mode and download a program with expanded data files.
Be Carefull.

Doug
 
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