Downloading with PID

[Controls Guy]

If you open a project from disk and do File -> Save Project -> To PLC that will get all non-ladder elements such as PID loops, manual I/O config and so on, right?  Or do you have to go into the PLC -> Setup -> PID dialog, read from disk, and then write to PLC?

I had a customer who reloaded a program and had no PID loops.  I think they probably opened the file, went online with "Use Disk" and clicked the "Write to PLC" button.

I want to make sure I give them correct instructions on how to do it so the PID loops and other stuff gets downloaded.

[franji1]

PID Setup configuration is stored in System V, with references to User V that contains the ACTUAL PID loop data (tuning constants, PV, SP, Output, etc.).  Hence, you must download the PROJECT (i.e. PROGRAM and DATA) to get your PID settings into a DL PLC.

If the customer ONLY hits the Write to PLC button on the Online Toolbar, this only writes the PROGRAM.  Or, if the customer NEVER SAVED their project to DISK or NEVER SAVED their PID Setup configuration and PID loop data to DISK from the two PID dialogs, then when they write their PROJECT to the PLC, it will write the previous values that were last saved to disk(zeros?).

[franji1]

I forgot to mention - this behavior is all with DirectSOFT.  If you use the free DNLoader tool, it sucks up ALL the Retentive memory and stores it on disk, then lets you write it back to a PLC at a later date - great for OEMs that are downloading the same program(s) over and over again.

I guess if the user stuck their PID data in non-retentive User V, or they tweaked the default retentive range to clear SYSTEM V, then this may not work either!   

[Controls Guy]

OK, I told them right then.  I told them to use "Save Project -> To PLC", and I wanted to make sure that would do it without having to transfer PID setup in a separate step.

Thanks, Mark.

[Greg]

There's a chart that shows what is saved by what:

http://www.hosteng.com/FAQFiles/DSP%20save%20and%20load%20chart2.pdf

[b_carlton]

Interesting - I did not know that T/C accumulator values are not saved/written even during a 'Save Project'. This doesn't show the status of communication port setups but I believe they are not saved/restored either. We do our secondary port setups in ladder for that reason.

I also have avoided using the T/C accumulator area even if I was not using those timers or counters. This is another reason to not do that.

[Greg]

Regarding "System V-memory", it has a Note (1) on it that says:

"(1) - System V-memory contains retentive ranges, etc., but does NOT save PLC password NOR comm port settings, NOR watchdog settings"


Regarding "Timer/Counter Accumulator Memory", it has a Note (9) on it that says:

"(9) - Values are never automatically written. To write them manually (to file or PLC) you must use Memory Editor"

[b_carlton]

Dang, these eyes are getting too old.

[Controls Guy]

There's a chart that shows what is saved by what:

http://www.hosteng.com/FAQFiles/DSP%20save%20and%20load%20chart2.pdf

Cool chart!  Thanks, Greg.  I'll make sure to keep a link to that.