cUTLER hAMMER HMI PanelMate Epro Pushbutton Suck on in PLC

[darrenj]

Tom...My application (Panelmate 5000 with a modicon Quantum) uses only momentary buttons..i dont think you can have a maintained button.( To maintain you have to do it in logic)

The screens do not "Hang"..what happens is if you push the start button sometimes the plc doesnt see you releasing that button so the logic stays true..most times if you push the button again it will then see the release.

 

[edwardel22]

Ok Updated The Firmware So We Will See If Anytime Soon The Buttons Get Stuck, And Ill Keep Ya Guys Posted. But This Happens On All 4 Of The Panelmates I Have In The Plant, All Momentary Buttons, So Its A Problem On The Panelmate Problem Not The Plc Side, So I Shouldnt Have To Change Any Of The Logic. Call Me Lazy But I Hate Making Changes To An Already Good Working Imposible Ladder Program Made By In Integrater. Plus Im A Vb And Hmi Programmer, So Alot Of This Plc Language Is New To Me.

 

[Steve Bailey]

The way momentary pushbuttons are supposed to work is that when the operator touches the PB object, the PanelMate writes a 1 to the associated bit in the PLC. When the operator removes his finger, the PanelMate writes a 0 to that bit.

Stuck Bit Syndrome is caused by the PLC not receiving the 0. If the PLC doesn't receive the 1 when the operator first touches the button, the operator compensates by touching it again (usually a little bit harder than the first time. There is no corrsesponding compensation for when the PLC misses the 0.

How is the PanelMate communicating with the PLC? If the PLC is not getting the 0, one possible reason is excessive network traffic causing some packets to be lost. Of course, that doesn't apply if you're using serial point-to-point communications.

When you updated the PanelMate firmware did you also get the latest and greatest version of the communications driver for it?

 

[edwardel22]

yeah updated all software and firmware that cutler hammer sent me that they say may have casued the problem. the panelmate is communicating RS 232 with the plc. yeah once they hit the button it does usually turn from a 1 to a zero but one out of every million times a button get suck with a 1 in the plc, and you have to go online in the program and toggle the bit and then everything is ok.

 

[Steve Bailey]

With serial communications the only thing I can think of that would be causing the PLC to miss the turn-off would be that the message to write the zero is getting lost. One thing that could cause that is if the PanelMate has to generate such a large number of read and write requests that occasionally a buffer overflows and some data requests get lost.

A PanelMate (and most other HMIs) will request from the PLC whatever data it needs to keep the displayed screen updated. It will also request from the PLC whatever it needs to update any alarms that have been defined.

If the person who designed the screens for this application was careful, he minimized the communications overhead by placing all the data that the PanelMate needs in consecutive addresses in the PLC. All too often application designers dont bother.

If one screen has a mixture of I, O, B3, and N7 addresses, that's a minimum of four transactions to refresh it. One read request for each memory type. If the addresses are widely separated, each memory type might required multiple read transactions. If there are a lot of alarms defined, that gets added to the burden. Too often, I see applications where just about every tag has alarm conditions attached to it. It seems like the designer figured it's better to have an alarm and not need it than to need an alrm and not have it. It aint necessarily so.

In short, if you take a closer look at the application, you may find that there are some things you can do to minimize the chances of stuck pushbuttons.

 

[Sliver]

Just experienced this issue with a panelmate powerpro 3000.
Found two inputs from the HMI stuck on in the PLC (984-685E).
First one cleared after disabling off and reenabling.
Second one returned after disabling and only stayed off after going to the panelmate page configured with that function and pressing it. This is the first time I have seen it in many years of using this product. Just wanted to thank the earlier posters for the great reference material provided by this thread.

Brian.