Slow Panelview Plus

[Vikingson]

I inherited a system using an ML1200 connected to a PV+ 600 through RS-232 DF1 cable. The operators have been complaining non-stop about how slow the screen loads are on this beast(up to 15sec). The scan times don't seem unreasonable(35-50 X 100usec), but the program uses no indexing and looks ugly. I don't have the project file for the PV+, but when I decompiled the .mer I was astouded by how many screens(130) and macros(70) where used. I'm just getting my feet wet in the PLC world, but it seems crazy to have 20 copies of the same screen for entering data? I can't post the program public, but would anyone be willing to get me some ideas?

Yes, I did do a search, but I couldn't find any train wrecks like mine.

 

[SNK]

What is your Comm speed?
You can do up to 38.4K I think on the 1200.
(Realistically speaking though, that is not the problem, even 9600 should be fast enough to view data on screens)

 

[Gil47]

I have 2 of PV+ that have trends that eventually start running slow, and I power them down and re start the projects, about monthly.
Probably some form of memory leak.

 

[69FIREBIRD]

have a look at alarms and data logs - I beleave that their polling actions can slow down screen loading / refresh.

 

[RichBlunt]

sure seems like a lot of screens, 130 screens on a pv600, strikes me as bad design

 

[Vikingson]

I agree about the design. I have a feeling the programmer did not know how to use tags or indexing. I hadn't thought of the trending causing this because it only has five analog points. If anyone has the time to take a peek I could send it out. The macros are a real mystery to me though. It almost seems like the HMI is being used as a CPU.

 

[Ken Roach]

That's a LOT of screens for a little PV600. Anytime somebody is using a great many macros it sets off warning bells for me that they are trying to program around a lack of understanding.

My guess is that many of those screens are set as "on top" and not "replace" and therefore stay active in memory and accumulate, bogging down the terminal.

Really can't say without examining the application myself, but you may have a lot of opportunities to improve this application.

Regarding the update times, you can often improve performance by actually turning down the update rate because you don't overload the communications subsystem with new requests while it's still working on the old ones. Increase the update rate to at least 250 ms or maybe 500 ms.

Is the slow update for a screen change, or just an update of an indicator on screen ?

 

[Vikingson]

Is the slow update for a screen change, or just an update of an indicator on screen ?[/QUOTE]

On screen changes. For example, when an operator selects a process to run the unit is slow to bring up the verification screen. It is even slower to bring up the status screen after the start button has been pushed.

Most of the screen are replace screens.

When I look through the MPB settings I noticed that some of the hold times are very long (5 sec). I wonder if that was done because of slow comms with the CPU? (baud rate is 19.2K)

BTW thanks to all your help so fare everyone, I'm still trying to get the big picture together in my head on this and your ideas are helping a ton!

 

[RichBlunt]

I dont even know to look at it to know that you should redo and sort it out. I couldnt imagine an application that uses that kind of hardware which would need that many screens, it screams at me that it should have at least a slc with a pv1000

 

[Vikingson]

Rich, Great point and I can't agree more, but companies are more concerned with thier profit margin than customer satisfaction right now, so I'm stuck with this. I'd love to put a compactlogix in it, but I don't have that power.

I think the equipment could work if programmed correctly. The process is fairly simple, but I don't think the programmer knew how to deal with all the duplication correctly. I.E. having unique screens for all 10 processes instead of using the CPU to load the active process into tags.

I'm still not convinced that the number of screens is the problem. There is plently of memory available. I think it has more to do with how data is being moved to/from the CPU, or something like trending slowing down comms.

 

[504bloke]

Can you post the PV+ application (Use The Application Manager to make a backup)

edit: Whats the weather like out there (MN) at present? I have an old school friend in Minnesota.