Siemens SIMOTION Function Manual page 34

Synchronizing SIMOTION devices with a higher-level bus cycle clock
3.3 Synchronization of a SIMOTION device with an isochronous DP master interface
Figure 3-5 Example configuration for synchronization of a SIMOTION device which has an isochronous DP master interface
with a higher-level PROFIBUS DP cycle clock
Figure 3-6 Sample configuration for synchronization of a SIMOTION device which has an isochronous DP master interface
with a higher-level PROFINET IO cycle clock
Synchronization sequence
Following a configured/programmed system startup, the SIMOTION_2 device with the
interface configured as an isochronous DP master (with drives as DP slaves) is to be
synchronized with the higher-level bus cycle clock determined by the SIMOTION_1 device.
The interface which receives the higher-level bus cycle clock (DP slave in PROFIBUS DP,
sync slave in PROFINET IO) automatically synchronizes itself with the defined bus cycle clock.
Synchronization of the isochronous DP master interface on the SIMOTION_2 device with the
higher-level bus cycle clock must be activated by users themselves using a system function.
The user can thereby determine the time of synchronization and take suitable precautions,
such as deactivating affected DP slaves, to avoid system failures caused by the
synchronization process. See following sections: "Procedure for automatic synchronization"
and "Procedure for user-controlled synchronization".
Preferably, synchronization should be started while the SIMOTION devices are ramping up (in
the StartupTask), before the drives start to move.
Only after successful synchronization has been completed are the isochronous DP master
interfaces synchronous with the higher-level bus cycle clock.
34
Basic Functions for Modular Machines
Function Manual, 04/2014