Network Variable Subscriber

The BeckhoffTwinCAT Real-Time Ethernet solution contains from TwinCAT v2.9 on the ability to configure variables for deterministic data exchange between several TwinCAT-based controllers. The last could be other TwinCAT PCs or CX100x controllers. For this solution it is required to configure the Ethernet Miniport (Real-Time) I/O device type first.
For an Overview of TwinCAT Real-Time Ethernet devices, see..

The Subscriber is the receive-type variable of the TwinCAT target system. It receives values from the Publisher variable of the networked TwinCAT controller.

"General" dialog

Standard dialog as for all TwinCAT I/O devices. Nevertheless, a descriptive name for this Subscriber should be edited here. Additionally, a useful comment (i.e. about the Publisher the data is coming from) could be very helpful.

Diagnosis

Inputs
Variable	Description
FrameState	This variable is currently not in use at subscribers

Outputs
Variable	Description
FrameCtrl	This variable is currently not in use at subscribers

Context menu

Insert Network Variable: Calls the following dialog:

Browse for Computer: Calls the Choose Target System dialog.

Browse for File: Calls the file selection dialog for existing TwinCAT System Manager project files (*.tsm). If Publisher variables have been found in the selected file, these variables get listed in the Name, Id, Size, Type section of above dialog.

Create new Variable: Calls the Insert Network Variable dialog described below.

"Insert Network Variable" Dialog

Name: A descriptive name for the subscriber variable should be edited here.

Id: ...

Comment: Space for a helpful comment about this subscriber variable.

Type: Lists available data types for this variable. The appropriate type must be selected here. This could be standard data type, an array or a complex structure.

If e.g. the process image of the configured PLC project contains a user-defined data type (i.e. a structure) with the name 'MyType', it would show up on the list like shown above.

Subscriber variable - Inputs

Variable	Data type	Description
VarState	UINT	This variable is currently not in use
Quality	UINT	This variable shows how "old" the value of this subscriber variable is. Means, every 100μs the data variable is not updated this value gets increased by 1. This could happen e.g. when the link of the network connection is lost. After re-establishing it, the value is set back to 0 again. Max. value of Quality is 65535.
CycleIndex	UINT	This variable value increments with every I/O cycle the publisher does. The subscriber extracts this value out of the Ethernet frame.
VarData	as specified	To be linked to input variable (e.g. to PLC input).

Variable	Data type	Description
VarCtrl	UINT	This variable is currently not in use