run, rem or prog

[a11anjones]

Hello, I have an issue in work whereby there are a couple or glitches in the control. But I have noticed that the plc run, rem and prog switch is in the rem keyswitch position. I believe that the switch should always be in the the run position if running is in auto. Nobody at the site seems to know why it is in this position, I would like to switch it over to run but am hesitant as it is the same on all four of the plcs on the network. Does anyone know which position the keyswitch should be. Thanks.

 

[TConnolly]

If you wish to modify the program online over your network, or change the mode of the PLC over the network, then the keyswitch needs to be in the REM position. If you switch the keyswitch to the RUN position then the program can't be changed and the mode cannot be changed via software until the switch is returned to the REM position. Switching it to the RUN position will not make the PLC run better. Its a matter of preference. If you do switch to run and later decide to make a programming change you will need to remember to switch it back.

 

[Eriond]

Rem run allows the processor's program to be edited without interrupting the plc operation (using a programming device). Unless you are programming the PLC, there is no difference in how the PLC operates in Run or Rem Run.

 

[realolman]

I can tell you from experience that you will look and feel like a doofus if you post on this forum complaining of being unable to edit online, if you have the key in the run position.

 

[kiwi sparky]

If Key switch is in "RUN" PLC will operate like normal (outputs going on and off like commanded, timers timing etc). Programming is not possible and mode cannot be changed to "PROG" from programmers laptop. If Keyswitch is In "PROG", programming is possible, PLC will not be in run mode (no outputs on, no timers timing etc) and PLC cannot be switched to run mode from programmers laptop. If the Key switch is in "REM" it means that a connected computer (programmers laptop etc) can change processor from "RUN" to "PROG" remotely and do online edits. It is my preference to leave the keyswitch in "REM" so I can work from a central location (all PLC's networked) and do edits/mods as required. In some circumstances we switch key switch to "RUN" and remove the key. That way if edits are to be made, the programmer will need to come to me to get key first. (critical process' like pasteurisers)

I Type to slow. Sorry for the double up explanation

 

[demmons]

I can tell you from experience that you will look and feel like a doofus if you post on this forum complaining of being unable to edit online, if you have the key in the run position.

Thats not as bad as troubleshooting a program for about ten minutes...then realizing you are not online

 

[a11anjones]

Thanks for the tip, I had a feeling it had something to do with remote control obviously but was not sure quite what. I have never needed to use REM, I have always put the controller back into RUN since day 1. Atleast now I know the faults I have do not have anything to do with this switch position. Thanks again

 

[TConnolly]

Thats not as bad as troubleshooting a program for about ten minutes...then realizing you are not online

Been there. Done that. More than once.

However, technically, its usually not the program that is being troubleshot.

 

[504bloke]

So what are the faults you have ?

 

[leitmotif]

So what are the faults you have ?

Please let us not get so personal.

Dan Bentler

 

[Dua Anjing]

So what are the faults you have ?

My Wife says I'm too gullible, and she's probably right I mean why would she lie ?

 

[robertmee]

Been there. Done that. More than once.

However, technically, its usually not the program that is being troubleshot.

Ha, I can top that. How about going online and try to troubleshoot a problem and then realizing your connected to the wrong processor 'cause none of the comments are making any damn sense.

 

[Ron Beaufort]

the following common misconception hasn't come up during this thread – but I'm going to include it here just for completeness ... note: this is for Allen-Bradley platforms – other brands might be different ...

the terms "online" and "offline" are very often confused with the (completely unrelated) concepts of "Run" and "Remote" and "Program" ...

tip: "online" and "offline" have to do ONLY with whether or not you are COMMUNICATING with the processor using your programming terminal (computer) ...

specifically: "online" and "offline" have NOTHING/ZERO/ZIP/NADA to do with whether (or not) the processor is actually executing the ladder logic and/or controlling the system's field outputs ...

graphic illustration:

Bubba frantically yells over the walkie-talkie: "Quick! Take it offline! Take it offline!" ...

up in the control room, Cletus obligingly clicks "Go offline" on the programming computer screen ...

unfortunately the machinery keeps running right along - and now Cletus has to get back "online" again in order to actually take the system out of the "Run" mode ...

which might lead right into a discussion of hardwired E-Stops - and conveniently located disconnect switches ...

 

[Sreyes]

If Key switch is in "RUN" PLC will operate like normal (outputs going on and off like commanded, timers timing etc). Programming is not possible and mode cannot be changed to "PROG" from programmers laptop. If Keyswitch is In "PROG", programming is possible, PLC will not be in run mode (no outputs on, no timers timing etc) and PLC cannot be switched to run mode from programmers laptop. If the Key switch is in "REM" it means that a connected computer (programmers laptop etc) can change processor from "RUN" to "PROG" remotely and do online edits. It is my preference to leave the keyswitch in "REM" so I can work from a central location (all PLC's networked) and do edits/mods as required. In some circumstances we switch key switch to "RUN" and remove the key. That way if edits are to be made, the programmer will need to come to me to get key first. (critical process' like pasteurisers)

I Type to slow. Sorry for the double up explanation

I was told that if you power down a machine, turned the plc's key to prog and wait for the machine to fully restart, some glitches could be fixed. Thoughts??

 

[ianingram]

I was told that if you power down a machine, turned the plc's key to prog and wait for the machine to fully restart, some glitches could be fixed. Thoughts??

My thought is that the machine won't restart if it is in prog mode