BECKHOFF KL6904 - Manual (Page 41)

Operation
KL6904 39
4.2.11 Communication between TwinCAT controllers
The MASTER_MESSAGE and SLAVE_MESSAGE data types are used for communication between two
or more TwinCAT controllers via network variables.
Associated variables have to be created under Publisher and Subscriber on the communicating
controllers.
During TwinSAFE communication one side acts as the master, the other one as the slave.
This results in the following data types:
TwinSAFE Master Publisher MASTER_MESSAGE
TwinSAFE Master Subscriber SLAVE_MESSAGE
TwinSAFE Slave Publisher SLAVE_MESSAGE
TwinSAFE Slave Subscriber MASTER_MESSAGE
The link with the via TwinSAFE logic terminal KL6904 is established with the following dialog:
The connection created must now be made known to the TwinSAFE logic terminal. This is done by
marking the TwinSAFE connection list and pressing the right mouse button.
The variables of type MASTER_MESSAGE and SLAVE_MESSAGE are now displayed, and both (In/Out)
have to be selected.
The selection is confirmed via the OK button.