BECKHOFF CP-Link3 - Manual (Page 66)

Page 66
The host PC network variable can now be linked with PLC or task variables.
Accessing Bus Coupler outputs:
For accessing the outputs of the Bus Coupler a "Subscriber" is added to the client RT Ethernet device and a "Publisher"
to the host RT Ethernet device.
One or more network variable(s) are added to the host PC Publisher according to the PLC or task variables to be
mapped on the Bus Coupler outputs. The Publisher network variable, "Pub-Var CPX8XX Outputs" in this example, is
linked with the corresponding PLC or task variables.