Rockwell Automation 1756-SYNCH ControlLogix SynchLink Module User Manual - Manual (Page 47)

Publication 1756-UM521C-EN-P - July 2004
SynchLink Module Features 3-19
For more information on configuring your SynchLink modules, see Chapter 5.
Dependence on SynchLink is Not Required
• The module is a Time Slave on SynchLink.
• The module is the CST Time Master of the local chassis.
• You MUST have selected another module on the fiber optic
cable to be the SynchLink CST Master.
• If your 1756-SYNCH module uses firmware revision 2.18
or greater and communications with the SynchLink CST
Master are not present at power-up, the module
automatically becomes the Time Master of its local chassis.
If a Time Slave 1756-SYNCH module becomes the Chassis
CST Master without the SynchLink CST master, then the
slave chassis is running unsynchronized motion.
Unsynchronized motion may be acceptable when
troubleshooting or performing machine maintenance. When
synchronized motion is required the application logic in the
slave chassis must check the proper status bit in the slave
1756-SYNCH module.
• If your 1756-SYNCH module uses firmware revision 2.10
or earlier and communications with the SynchLink CST
Master are not present at power-up, CST-dependent
features will not start operating until the communications to
the SynchLink CST Master are restored.
• If communications with the SynchLink CST Master are
broken after operation has begun, the module continues to
relay time and acts as Chassis CST Master. In this case, the
chassis is running unsynchronized motion that you must
account for in your application’s logic.
IMPORTANT: If your 1756-SYNCH is running unsynchronized
motion (i.e. because the connection to a SynchLink CST Master
either broke or never existed), when communications are resumed
with the Master over the fiber optic cable, you must do the
following to become synchronized with the CST Master:
• Stop all motion connected to this chassis.
• Reset the 1756-SYNCH module via application ladder logic
or RSLogix 5000.
Dependence on SynchLink is Ignored • The module is a Time Slave on SynchLink.
• The module is the CST Time Master of the local chassis.
• You MUST have selected another module on the backplane
to be the SynchLink CST Master.
• The module acts as an unsynchronized Chassis CST Master.
In this case, the module ignores the SynchLink CST Master
at all times, including module power-up.
This option is expected to be a temporary mode of
operation.
Table 3.7 Possible SynchLink Configurations
This configuration: Means: