UA_MonitoredItemAdd – OPC UA Client Function Blocks for IEC 61131-3

FB-Name			UA_MonitoredItemAdd
This Function Block can be used to add handle that values are updated by subscription.
VAR_INPUT
B	Execute	BOOL	On rising edge monitored item will be added to a subscription.
B	SubscriptionHdl	DWORD	Subscription handle.
B	NodeHdl	DWORD	Node handle.
B	NodeAddInfo	DWORD	See UANodeAdditionalInfo. Specifies the attribute and IndexRange.
B	Timeout	TIME	Time to response.
VAR_OUTPUT
B	MonitoredItemHdl	DWORD	Monitored item handle.
B	Done	BOOL	FB has completed its task.
B	Busy	BOOL	The FB is not finished and new output values are to be expected.
B	Error	BOOL	Signals that an error has occurred within the FB.
B	ErrorID	DWORD	Error code.
VAR_IN_OUT
B	Variable	Vendor specific		To be defined by vendor.
B	MonitoringSettings	STRUCT		See 9.1 UAMonitoredSettings (phased out structured data types)
Notes: VAR_IN_OUT: „Variable” as would provide best type save solution for users: The client firmware is able to map the UA memory layout to the controller layout. The firmware client can receive the type definition from the OPC UA Server. Workaround would be to provide a byte array as “Variables” and the firmware client just provide the blob (UA memory layout – so called “raw data”) into that byte array. A “Variable” could be the name of the variable so the internal firmware can get address, length, data type of variable.