Rockwell Automation 1756-SYNCH ControlLogix SynchLink Module User Manual - Manual (Page 35)

Publication 1756-UM521C-EN-P - July 2004
SynchLink Module Features 3-7
Multiple Port Communications Formats in Single Module
You must set a communications format for receiving data (Receive Port
Communications Format) and transmitting data (Transmit Port
Communications Format) in each SynchLink module. The following
requirements apply to communication format choices:
• If a SynchLink module does not receive data (e.g. a SynchLink
Time Master in a star or daisy chain configuration), you must
choose the No Receive Data Receive Port communication format.
• If a SynchLink module does not transmit data (e.g. an end
node), you must choose the No Transmit Data Transmit Port
communications format.
• The receive communication format for any SynchLink module
that receives data must match the transmit communications
format of the upstream node in the system. For example, if the
Time Master SynchLink module uses a 2 Axis Transmit Port
communication format, the SynchLink module physically
connected to the Time Master must use a 2 Axis Receive Port
communications format.
• If a SynchLink module is used to provide CST signals to remote
I/O chassis, you can choose any communication format except
No Receive Data, Listen Only or No Transmit Data. CST signals
are used in the remote chassis to synchronize I/O timestamps. In
this case, the data words transmitted over SynchLink are
not used.
IMPORTANT
The receive and transmit on the same module do not
have to match.
Also, once the module is created, you cannot change
the communications format. You must delete and
recreate the module.