Logix5000 - How to retain memory between downloads

[mainstreetmark]

This oughta be a simple one --

I'm noticing that if I'm online with a Logix5000 PLC, and "save" the project (thereby uploading memory), and later go offline, make a change, and download it again, the PLC's memory gets reset to soem virgin values. None of my setpoints remain.

What do you think i'm doing wrong?

 

[Oakley]

Is there a startup routine that has logic that sets initial values?

 

[mainstreetmark]

Startup is one thing, yes, but what about the CURRENT things - counters and so forth.

 

[jkerekes]

When you download to a ControlLogix processor, the tag values are also written to the processor. You can't just download the "code" without also downloading the tag values that you have in your offline project.

 

[mainstreetmark]

Agreed. But why doesn't the current tag values get uploaded, so that the next download simply pushes them back down?

 

[rdrast]

Agreed. But why doesn't the current tag values get uploaded, so that the next download simply pushes them back down?

It does on all of my processors here. When you are online, and do a save, do you select to upload current tags? If you do, they will be pushed down again on a download.

The start-up routine could be changing them again though, or values may have been changed between your upload and your download.

Why not just make the changes online?

For completeness, I should ask what processor firmware version you are using.

 

[mainstreetmark]

It does on all of my processors here. When you are online, and do a save, do you select to upload current tags? If you do, they will be pushed down again on a download.

The start-up routine could be changing them again though, or values may have been changed between your upload and your download.

Why not just make the changes online?

For completeness, I should ask what processor firmware version you are using.

Logix v16 does not allow the editing of UDTs and AOI's while online.

And yes, I *am* uploading tags when I save, it just is being dumb, i guess.

 

[rdrast]

Ahhh... If you are losing UDT/AOI definitions, that makes possible sense then. You might want to try using the "Tag Upload/Download Tool" included with the RSLogix 5000 installation, that may work.

Upload them with that first, DL the program, then DL the tags.

Changing the definitions is probably wiping out some or all of the UDT/AOI data due to alignment changes in the structure.

 

[mainstreetmark]

I'll have to pay attention to that. I don't *think* i'm changing the AOI definition, but it would make sense that it'd cause this issue.

It'd be neat if they had a Run handler that ran everytime the CPU went into RUN.

 

[rdrast]

I'll have to pay attention to that. I don't *think* i'm changing the AOI definition, but it would make sense that it'd cause this issue.

It'd be neat if they had a Run handler that ran everytime the CPU went into RUN.

Well, write one. Two ways. One, is the "Power-Up Handler" routine (just under the controller tags in the application tree). Another is in routines that need initialization, use the S:FS (first scan) bit to run an initialization routine.

ETA- the "Power-Up Handler" I believe only runs after a powerdown, I'm not sure about a download of a new program. I generally just use the XIC S:FS JSR _000_Initialize myself.

 

[mainstreetmark]

Brilliant!!