Gateway Tag Change Script or Local Tag Change Script

[Robert_Thompson]

Is there any difference between the Gateway Event, Tag Change and the Script function on a tag for value change? I see the Gateway Event can be configured for several items including tag change. I'm just wondering if I should make the script a gateway event or leave it a local tag change. The problem I see is the tag remains on and the tag will not run a second time.

def valueChanged(tag, tagPath, previousValue, currentValue, initialChange, missedEvents):
	trigger=system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/GetPLC912Data.value")
	trigger=trigger[0].value
	if trigger == 1:
		recname = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Recipe_Name.value")
		recname=recname[0].value
		EndDate = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Times_Input_912/StopTime.value")
		EndDate=EndDate[0].value
		recipe = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Recipe_Number.value")
		recipe=recipe[0].value
		skid = 912
		StartDate = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Times_Input_912/StartTime.value")
		StartDate=StartDate[0].value
		unit = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Unit_Number.value")
		unit=unit[0].value
		params={"EndDate":EndDate,"Recipe":recipe,"RecipeName":recname,"Skid":skid,"StartDate":StartDate,"Unit":unit}
		ret=system.db.runNamedQuery("NXM_OEE","CIP/CIPInsert", params)
		PK=system.db.runNamedQuery("NXM_OEE","CIP/CIPGetPK")
		x=0
		for x in range(38):
			cond = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Step"+str(x)+"/Conductivity_SP.value")
			cond=cond[0].value
			pumpsp = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Step"+str(x)+"/Pump_SP.value")
			pumpsp=pumpsp[0].value
			EndDate = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Times_Input_912/Step"+str(x)+"/StopTime.value")
			EndDate=EndDate[0].value
			StartDate = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Times_Input_912/Step"+str(x)+"/StartTime.value")
			StartDate=StartDate[0].value
			stepname = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Step"+str(x)+"/Step_Name.value")
			stepname=stepname[0].value		
			stepnum = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Step"+str(x)+"/Step_Number.value")
			stepnum=stepnum[0].value		
			steptimesp = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Step"+str(x)+"/Step_Time_SP.value")
			steptimesp=steptimesp[0].value
			suptimesp = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Step"+str(x)+"/Supervision_Step_Time_SP.value")
			suptimesp=suptimesp[0].value
			tempsp = system.tag.readBlocking("[New Castle]NXN-HHC CIP/912_CIP/CIP_Report_Data_Input_912/Step"+str(x)+"/Temperature_SP.value")
			tempsp=tempsp[0].value
			params={"EndDate":EndDate,"PK":PK,"PumpSP":pumpsp,"StepName":stepname,"StepNum":stepnum,"StartDate":StartDate,"SVTimeSP":suptimesp,"TempSP":tempsp,"TimeSP":steptimesp,"CondSP":cond}
			if (EndDate <> "0002-11-30 00:00:00" and stepname <> ""):
				ret=system.db.runNamedQuery("NXM_OEE","CIP/CIPStepInsert", params)
	system.tag.writeBlocking("[New Castle]NXN-HHC CIP/912_CIP/GetPLC912Data.value",[False])

Here is the script for reference. The script runs when GetPLC912Data goes positive. Thank you for any comments.

[pturmel]

@Robert_Thompson

any difference

Oh, yes. Your script is very much unsuitable for definition on the tag itself. Some reading and further links:

PLC to Ignition Interactions

There are pros and cons. (Numerous discussions here on those.) But it is almost always preferable to system.util.invokeAsynchronous(). Starting new threads is a performance killer, and can run wild if you aren't careful. Discussions like these (and more, if you tweak the search terms): https://forum.inductiveautomation.com/search?q=gateway%20tag%20change%20event%20valueChange%20thread%20pool%20order%3Alatest If you have a particular need for valueChange scripting, but also need to not bloc…

[Robert_Thompson]

Thank you. I found some discussions about when to use a gateway script. I changed the script to a gateway function today. Thank you for the reply. Have a great weekend!