Upload Controller project while it's running

Hi,
Can the project in the controller be uploaded while it is running.

Depends on the controller and your definition of the direction of the transfer when you say "upload".

Many popular PLC controllers support an "upload" of a running project from the PLC to a PC running the engineering software, including most controllers from Allen-Bradley, Siemens, Schneider, Omron, Mitsubishi, etc.

Some PLC controllers, including some small and inexpensive ones, must be placed in a Stop or Program mode to perform an upload or download.

Please post as much context and detail as you can, and welcome to the PLCTalk Forum community.

The only problem that might occur during a running upload is the tag values may change while the machine is running, as the upload will take longer than one scan of the program, so the offline data might not compare

IE - temperature setpoint doesn't match process value but the heater isn't on or called for because when the BOOL tag for HeaterOn was uploaded it was OFF, but when the DINT tag for HeatPV was uploaded it dropped to where the heat should be on.

Aabeck said:

The only problem that might occur during a running upload is the tag values may change while the machine is running, as the upload will take longer than one scan of the program, so the offline data might not compare

IE - temperature setpoint doesn't match process value but the heater isn't on or called for because when the BOOL tag for HeaterOn was uploaded it was OFF, but when the DINT tag for HeatPV was uploaded it dropped to where the heat should be on.

Click to expand...

This is potentially true, but not all controllers include live process values as part of the upload.


I know Siemens PLCs don't. What you upload (besides the code) is the data structure and the "start value", which is the value the tag initializes at when you power on the PLC. Extra steps are required to upload live data.

Yes, Mitsubishi does the same thing. Have to upload the program and then the data otherwise you get a popup about being uploaded together.

I was thinking RSLogix/Studio 5, 500 & 5K

Hi, it is a AB controllogix. With upload I mean getting
The project from the plc to the pc. Do you need to put it online, stop,etc.
Should I stop the equipment ? What would be safest procedure?

Thanks for the help

Abn said:

Hi, it is a AB controllogix. With upload I mean getting
The project from the plc to the pc. Do you need to put it online, stop,etc.
Should I stop the equipment ? What would be safest procedure?

Thanks for the help

Click to expand...

Uploading from the PLC to the PC is required to go online with the controller. No need to stop the equipment for an upload.

Abn,

the only thing you have to remember is that when you upload the program from the plc to the pc.
if you need to save the timer/counters, and other data, you save the state of all the I/o, bits... as well.
when you download the program back into the plc (if the cpu dies, looses the program) you download the state of everything, including I/o. this can be a problem. make sure the machine has no one around and the e-stop is pushed to kill the power to all the I/o ( our company procedure)

james

One other point is to try and make sure the machine/process is in it's idle state or home position and not running, this means you then have a snapshot of the data at a point where the machine/process is in it's ready to start state.
When downloading the program plus data it is best to have the machine in it's normal idle state so the snapshot data if uploaded in this state previously will mean the machine will be in a idle state and not liable to start when the processor is switched back to run.

Thanks a lot for the help

Jasondelane said:

Uploading from the PLC to the PC is required to go online with the controller. No need to stop the equipment for an upload.

Click to expand...

No, a full Upload is NOT "required". The only time you need to perform an "Upload" is if you haven't got the "offline" file, or the "offline" file is too old for "correlation".

Correlation is an automatic process (performed while going online) where the offline file, that you are trying to go online with, is updated by uploading just the changes that have been made in the controller since your project file was last online. Changes mostly made by someone else, or you didn't perform a "Save" when ending your last online session.

Correlation is required because the offline and online logic must be identical, so that RSLinx only has to collect Data to animate the display, and no Logic needs to be collected, as in earlier platforms.

Sometimes you can see the correlation happening, but you will always know if it has when you come to end your programming session. A message will appear that says "Changes have been uploaded from the controller. Do you want to save these changes to your project file" (or along those lines).

The weird program on that is Automation Direct's DirectSoft.

When you connect to the PLC with an offline project open it will verify and if the projects differ it will ask if you want to use the disk (offline) copy or the PLC copy.

If you select PLC it will upload the project, if you select disk it will connect and show you the status's of the PLC's bits, words, timers, counters - but not necessarily the right bits and values as the offline project and the online monitoring will be way off.

IE - XIC X0 is OFF but the output Y3 is shown ON, a timer with a preset of K15 will report a accumulator value of 600, still be timing and the DONE is not on yet because that timer has a preset of K1000 in the PLC.

I always thought that was unusual it would let you do that and shouldn't.

On some platforms uploading a modified project from a PLC can cause the comments on the documented file to go out of line & in Siemens uploading DB's the wrong way will remove the structure text. The best way in my opinion, is to compare the off line file & if there are differences i.e. extra rungs then code them in the offline file then upload. If the comparison shows no differences in the code then it can be useful to upload the data just in case some variables i.e. Adjustable ones for example scaling or time setpoints that might need to be changed via HMI or scada (I'm referring to engineering setup pages generally).
Again I re-iterate the need to make sure the machine is in a safe start position and not running so that any variables are consistent with a start position and not likely to cause a problem on a full download.