OPC UA Constants and Variables

Overview

OPC UA variables are used to hold data retrieved from an OPC UA server. Variables must exist in DataXchange and then be mapped to OPC UA items.

OPCUA Source Variables

DataXchange includes the following variables predefined:

	Variable Name	Notes
	Alarm Code [OPCUA.alarm_code]	Returns the value mapped as the alarm code
	Alarm Detail [OPCUA.alarm_detail]	Returns the value mapped to the alarm description
	Alarm Status [OPCUA.alarm_status]	Returns the value mapped to the alarm status
	Cycle Status [OPCUA.cycle_status]	Returns the value mapped to the cycle status
	E Stop [OPCUA.estop]	Returns the value mapped to the e stop
	Part Count [OPCUA.part_count]	Returns the value mapped to the part count
	Program Number [OPCUA.program_number]	Returns the value mapped to the program number
	Connected Time [OPCUA.connected_time]	Returns the amount of time in seconds since a successful connection to the Source.

The following variables hold the value for the previous poll from the device.

	Variable Name	Syntax
	Alarm Code (Previous)	[OPCUA.prev_alarm_code]
	Alarm Detail (Previous)	[OPCUA.prev_alarm_detail]
	Alarm Status	[OPCUA.prev.alarm_status]
	Connected Time (Previous)	[OPCUA.prev_connected_time]
	Cycle Status (Previous)	[OPCUA.prev_cycle_status]
	E Stop (Previous)	[OPCUA.prev_estop]
	Part Count (Previous)	[OPCUA.prev_part_count]
	Program Number (Previous)	[OPCUA.prev_program_number]

OPC UA Custom Variables

In addition to using the predefined variables, DataXchange has the ability to create custom variables for the OPC UA source. OPC UA variables can be added or modified by selecting the Variable drop down and then the OPC UA menu item on the DataXchange tab.

Custom variables will then show in the expression builder when defining expressions. For example, the following will show after an custom variable named stack_light was created for OPC UA.

Variable Name

Notes

Custom Variable

[OPCUA.stack_light]

Returns the data from the custom mapping variable

The following variables hold the value for the previous poll from the device.

	Variable Name	Syntax
	Custom Variable (Previous)	[OPCUA.prev_stack_light]

Once the variables have been defined they need to be mapped to OPC UA data items. The mapping is done at an individual equipment level since this may vary from equipment to equipment.