How to force values in RSLogix 5000

[ndzied1]

We have a compact logix controller and cannot seem to be able to force values in the controller.

Enable forces are on but when we try to write values they do not stick? What are we missing?

Thanks,

 

[minaykha]

Did you put controller in remote mode ?

Is it other logic in program over write on your force value ?

Usually, Clt + T can be used to Force ON and OFF.

 

[defcon.klaxon]

Are you trying to force non-I/O tags? In Logix, you can only force the actual tag of an output module; they'll look something like "Local:13:I.Data.0". Tags like "HMIStopButton" cannot be forced, however.

 

[ndzied1]

Thanks!

I'll let our technician know and see if that does it.

 

[T Gibbs]

If something else is writing it off in the program it won't force. You can temporarily put an AFI ahead of it to allow it to be forced.

 

[defcon.klaxon]

Thanks!

I'll let our technician know and see if that does it.

Let us know how it goes. I'm literally working on AB at the moment so I would be happy to help. feel free to PM me. Was literally working out the subtleties of forcing this afternoon. Forcing analog I/O can be particularly challenging.

 

[amberman]

Let us know how it goes. I'm literally working on AB at the moment so I would be happy to help. feel free to PM me. Was literally working out the subtleties of forcing this afternoon. Forcing analog I/O can be particularly challenging.

Can you force analogue outputs? I just add an always open bit in line then just write in the value I want.

 

[Ron Beaufort]

some of you folks are confusing the procedure used to "TOGGLE A BIT" – with the completely different "FORCE an INPUT or an OUTPUT" procedure ...

the following link might be helpful ...

http://www.plctalk.net/qanda/showthread.php?p=537414&postcount=1

for FORCING an ANALOG input or output, you might be interested in the following ...

http://www.plctalk.net/qanda/showthread.php?p=673601&postcount=3

party on ...

 

[defcon.klaxon]

Can you force analogue outputs? I just add an always open bit in line then just write in the value I want.

You can, yeah. It's a bit of an odd process to get your head around though. If you go to the analog data tag, you can put the value you desire in the "Force Mask" column. The strange part to grasp is that you are forcing it and the output signal is responding, but it doesn't show you that *anywhere* in the tagname or code though. So if you have an output that activates an alarm and you force it, you won't get the alarm and anywhere in the code that output value is shown, it won't be your forced value.

You can imagine how frustrating that can be! Literally following the manual step for step and not seeing the output change in Logix. But if you clamp a meter to your output you'll see it change.

 

[amberman]

You can, yeah. It's a bit of an odd process to get your head around though. If you go to the analog data tag, you can put the value you desire in the "Force Mask" column. The strange part to grasp is that you are forcing it and the output signal is responding, but it doesn't show you that *anywhere* in the tagname or code though. So if you have an output that activates an alarm and you force it, you won't get the alarm and anywhere in the code that output value is shown, it won't be your forced value.

You can imagine how frustrating that can be! Literally following the manual step for step and not seeing the output change in Logix. But if you clamp a meter to your output you'll see it change.

Useful. More often than not I only use forces as part of an I/O check. The activity seems to be in line with the way AB handles forcing so although a bit odd at least it's consistent.