Add a timer before a tag get changed

[Odd-Simon_Simonsen]

Hello,

Is it possible to add an timer on the scripting menu on a tag?

I have an numeric label for the process value "PV", and an numering label for an setpoint "SP".

When the PV goes over the setpoint SP i have it automaticly pressing a One Shot Button trough scripting.
But I dont want it to be pressed right away, I want it to wait a few seconds before pressing the One Shot Button.

Is there possible to add a timer in the scripting menu of the PV?

Thanks

[nminchin]

Sounds like something that should be implemented in the plc..

Or, look at this

Best way to trigger a script after a time delay without pausing a script

Welcome to the world of non-deterministic operating systems. I was able to get a bit better performance by not running it through the alarm subsystem. UDT_Timer_millis.json (2.1 KB)

[lrose]

@Odd-Simon_Simonsen

Is there possible to add a timer in the scripting menu of the PV?

Place your script in a function and use system.util.invokeLater() with the desired delay.

system.util.invokeLater | Ignition User Manual

[Odd-Simon_Simonsen]

@lrose

Place your script in a function and use system.util.invokeLater() with the desired delay.

I tried this, but if the PV changes back down under the SP value it still pushes down the button after the delay

[pturmel]

You will not find a robust solution that runs in the user interface. You need repeating gateway logic that examines your conditions, sets timestamps, and acts upon past timestamps.

Just like a PLC would.

[Odd-Simon_Simonsen]

Is it possible to script the value of the button to 1 after the alarmEvent.state.isActive goes true? then I can use the alarm active delay to push the button iguess?

[lrose]

@Odd-Simon_Simonsen

I tried this, but if the PV changes back down under the SP value it still pushes down the button after the delay

Your function needs to re-examine the conditions then.

As @pturmel said using the UI to do this isn’t going to be robust. You can get close but there will be unhandled cases.

[pturmel]

@lrose

be unhandled cases.

Like, what do you want to happen when no client is open? Or not open to the window with that button? Or with a modal notification up that stops your scripts?

Or when you have more than one client open?

Really, this is not a task for your user interface.

[amarks]

This is absoluetly something that should be done in the PLC.
Here's my 2¢:

You'll want a UDT to organize everything.

1. OPC tag for the SP Process_SP
2. OPC tag for the PV Process_PV
3. Memory tag for the button-press delay Auto_Adj_PRE
4. Expression tag to detect when the PV exceeds the SP Auto_Adj_Req [{Process_PV} > {Process_SP}]
5. Memory tag used as intermediary before actually executing the update button Auto_Adj_INT
6. OPC tag for the button Update_SP_PB

2 different valueChange scripts should get the job done here.

1. Auto_Adj_INT.valueChaged()

def valueChanged():
	if currentValue != previousValue and not initialChange:
		if currentValue.value == 2:
			system.tag.writeBlocking(['Update_SP_PB'], ['1']) #psuedo-path

2. Auto_Adj_Req.valueChanged()

def valueChanged():
	if currentValue != previousValue and not initialChange:
		
		#PV > SP
		if currentValue.value:
			#get the delay
			delay = system.tag.readBlocking(['Auto_Adj_INT'])[0].value #psuedo-path
			system.util.invokeLater(maybeUpdate, delay)
			
		#PV < SP
		else:
			#reset INT to 0 - cancels the PB
			system.tag.writeBlocking(['Auto_Adj_INT'], [0]) #psuedo-path
			
		def maybeUpdate():
			#read current INT
			autoAdjINT = system.tag.readBlocking(['Auto_Adj_INT'])[0].value #psuedo-path
			#INT is still 1, update to 2 - triggering the INT's valueChanged script
			if autoAdjINT == 1:
				system.tag.writeBlocking(['Auto_Adj_INT'], [2]) #psuedo-path

Again, way easier in the PLC. Also, I am unsure if your oneshot button exists in the GUI or in the PLC, or how it gets reset

[amarks]

@Odd-Simon_Simonsen did not specify if this is a one-shot button on the GUI or in the PLC. I assumed that it was a button in the PLC.

[michael.flagler]

What exactly are you trying to accomplish? I think if you described what the end goal was, it would help everyone understand what you're doing. What is the function of the one-shot button? Is it tied to a PLC tag? Are you running a script to do something else?

While ideally this is something done in the PLC, if it's doing something in Ignition or a DB, or something else, sharing that information would help everyone else out.

[Odd-Simon_Simonsen]

Thanks everyone by your input. And sorry if what I tried to explain/ask for was very unclear.

I ended up setting up an alarm for the process value PV rising over the setpoint SP, this with the . And with this i added the Active delay property on the alarm.
I then went on the scripting on the same tag, with the Alarm Events > Alarm Active. Wrote what thag to be changed to 1/TRUE when the alarm is active:
system.tag.writeBlocking(TagPath, 1)

This ended up working and did what I tried to accomplish without changing the PLC code (due to old PLC and dont want to edit code thats havent been touched in years).