Momentary push button in iFix

[iluntasun]

Hello everyone,

Does anybody know if there is a way of simulating the behaviour of a FTV momentary push button on iFix?
I am trying to create a button that the user has to keep pressing for a couple of seconds before the command is actually sent. I looked around a bit and looks like there is nothing like that built in, but maybe somebody knows of any possible workarounds?

Thanks in advance!

 

[parky]

Never seen it but then again not done IFIX for a number of years, I have done it in the PLC (assuming you mean hold button until a couple of seconds have elapsed before it triggers) this is simple by putting the button onto a timer so the output of the timer only triggers if the button is held down for x seconds, or if you require the operator to keep pressing the button a number of times then use a counter, if button not pressed again within a short period reset the count so that if operated again say 5 seconds later it starts to count from 0, perhaps something like this could be done in a script rather than the PLC.

 

[Corsair]

I agree with Parky that the best way to approach these issues is usually in the PLC.

The interface appears to be the easiest way to do some things - but the PLC is ultimately responsible for how the system operates. That includes safety concerns. That's why I have never used the 'momentary on' functions that seem to be so popular with the Allen Bradley interfaces. If the shut-off communication fails you can get a 'stuck button'.

The PLC is the system that can make correct choices in the event of a PLC power failure, etc.

Setpoint bounding is another issue. Lots of space has been devoted to discussing these things on this forum.

The executive summary is that just because an interface like FTV can support something doesn't mean that it is a good idea to use it that way.

 

[iluntasun]

I agree that doing as much as possible in the PLC is best, but in this case I don't see how it can help me. I probably didn't explain well enough.

iFix will write a value to a tag in the moment that the button is pressed (in the script, "Private Sub commandbutton_click"), but how can the PLC know whether the button is still pressed or not? There doesn't seem to be a commandbutton_whilepressed or something like that.

If the button is still pressed, the PLC will reset the value when the timer is done regardless of whether the operator is still pressing the button. And it will execute the desired command after the timer is done, even if the operator releases the button in the screen before the timer is done.

Usually I would rely on a physical button for this kind of thing, but it is not an option in this case.

 

[drbitboy]

In some environments, there are several types of button "events" defined:

• ButtonPress or MouseDown - when the button is first depressed
• ButtonRelease or MouseUp - when the depressed button is released
• ButtonActivate or (mouse) Click - when the button is depressed, then released
• (mouse) DblClick - when the button is clicked twice witnin a given timeframe.

OP should check what is available with IFIX.

 

[iluntasun]

Spot on!

A quick glance on the PushButton object's list of VBA events revealed that both MouseUp and MouseDown exist. I can work with that.

Thank you!