Pushbuttons

[harryting]

A good general practice is to treat the HMI command and command to the device as two separate items. There are many reasons for this; communication glitch, allowing for multiple HMI, reboot of HMI or PLC, etc... In NO WAY you would want the HMI to issue the stop command even though I assume the Limitorque would not act on it once it reach it's destination. Treat the HMI command as a start/stop to a separate sequence to open/close the valve.

Also, if there's any chance of something gets stuck the valve, you would want valve fault logic where it stop the action and let "maintenance" open/close action taking over where you have to maintain the open/close to jog the valve to either end.

BCS, nothing. Keep in mind the HMI is basically doing a one shot and doesn't check the PLC status again. IE. HMI is not constantly syncing the database. To make PLC code works with various HMI I used to make this type of of logic

--| HMI Set 1 | -----------(Latch command)-----

--| Command |------------(Unlatch HMI Set)----

This also take care of slow communication

 

[Bering C Sparky]

Gomez, Thanks,

Ok, I follow that, just was not aware that this could be done.

I guess I was always under the impression that OTU worked only in conjunction with OTL.

So is this also possible to do with RS500, say you set B3:0/1 with a maintained button, can you unlatch it in the same mannor as you did here in LOGIX5000??

Thank you very much for setting me straight on this, I feel a bit foolish, but now I know.

Public humiliation is probably not the best path to take for getting an education but it sure does stick with you, and you dont soon forget those lessons learned.

(This forum is my best source for education, given my present location)

Thanks Again for the Schooling, and letting me participate. I learn something new every day here.

BCS

EDIT: Steve: thank you for the explanation also.

 

[Buzzen]

Gomez thanks for the narrative and the pictures. That's what I love about this forum, there is always someone wanting to lend a hand to help. And for the others who participated thank you as well....

 

[rdrast]

As an aside BCS, I ALWAYS incorporate a forcible unlatch for HMI PB's after the command has been read and executed, or after a time delay for momentary PB's that might be held in (think Jog, Inc/Dec PB's, etc).

I've seen too many times where (especially) FTView ME/SE will fail to write a reset value on a momentary PB, leaving it stuck on in the PLC.

Never seen that with Wonderware, or Red Lion HMI's, or even the old original PanelViews, but the FTView ME/SE is unreliable to the max on releasing momentary buttons especially.

 

[Bering C Sparky]

Thanks everyone for all the great information.

I certainly have not been incorporating these unlatch instructions in my PV applications but will begin doing so now.

I have basically learned what I know by looking at existing programs that were already functional when I got on these vessels.
So I have adopted the same format as these existing programs were written.

When I started here I did not even know what a PLC was, so it has been an up hill climb, teaching myself and trying to grab at the next bit of knowledge that hangs just over my head.

It is fun though and I enjoy it very much.

I am sure that alot of eyes roll, when I post on a subject and I am dead wrong in my belief and what I am saying. But getting called out on these items and shown the correct way or method helps me greatly.
Had I not participated in this post, who knows how long I may have walked around believing the wrong thing about Push Buttons on HMI's.

Thanks for your pacients and all your advice and help.
I do appriciate it and look forward to learning the next bit of information in the ever expanding puzzle that is automation.

I feel very fortunate to be able to draw from the wealth of knowledge contained here in this forum.

Regards,

BCS

 

[Buzzen]

I have tried this above mentioned application to unlatch the maintained PB on the Panelview. I tested the page by pressing the test display button and the PB held. It's not releasing the way you guys got it to. I then tried testing the application with ME and the same thing. I have the Next state based on:Current State. Am I doing something wrong?

The Unlatch becomes true and stays true, the Maintained push button tag never gets a zero written to it.

 

[harryting]

I have a tough time following your description of what's happening.

Post the section of the logic and a screen shot of how you configure the button on HMI.

 

[Buzzen]

here is some screenshots

 

[Gomez_]

In your button connection, hook up the indicator to the same tag. If that still doesn't work, try removing the one shot

 

[Bit_Bucket_07]

As an aside BCS, I ALWAYS incorporate a forcible unlatch for HMI PB's after the command has been read and executed, or after a time delay for momentary PB's that might be held in (think Jog, Inc/Dec PB's, etc).

I've seen too many times where (especially) FTView ME/SE will fail to write a reset value on a momentary PB, leaving it stuck on in the PLC.

Never seen that with Wonderware, or Red Lion HMI's, or even the old original PanelViews, but the FTView ME/SE is unreliable to the max on releasing momentary buttons especially.

I've seen "stuck" momentary pushbuttons in Wonderware, but only with larger applications that were "upgraded" from SuiteLink to DA IO Servers. A momentary HMI button is merely a set bit on down and reset bit on up function. If one of the writes fails, then you're PLC is out of sync with the HMI until the pushbutton is operated again.

I've seen this happen when operators repetitively click a button, rather than using the single touch and release that the button was designed for. You can see all of the failed write commands stack up in the log viewer whenever they do this on a highly loaded IO Server. It's difficult to "un-train" this behavior with some guys. They just feel like they're speeding things up by pressing the button as fast as they possibly can for at least 10 or 20 times.

 

[Buzzen]

Okay thanks, I will try that!

 

[harryting]

Buzzen,

Some of the pictures are hard to read but it seems you are missing some logic.

What I see you doing is the following

-HMI Set Tag to 1

@PLC
----|HMI Tag|----ONS-------------(U Valve)---

You don't want to unlatch the action before it's complete

HMI Set ValveOpen Tag to 1

--|HMI_ValveOpen|-----------------------------(OTL Opening Valve IO)---

--|ValveOpened FB|-----------------------------(OTU Opening Valve IO)--
                                                        |
                                                        |
                                                        --------(OTU HMI_ValveOpen)---

You can tie the button's indication to the same tag as command

ETA, I simplified the logic

 

[Buzzen]

what ended up working for this application was to take the oneshot out of the logic. The logic will now unlatch(maintained pushbutton) the valve when it is closed. I also added the same tag to indicator, don't know for sure if adding the indicator tag was the key. I haven't tried it without it. When the manual is not set the button will not work at all, which is what I want. I didn't want that maintained pushbutton to be holding the valve closed. Thank you all for the input it was as always very helpful. If there is anything that I am missing please don't hesitate to add your input.
Thanks again