Cycle Clock Generation And Synchronization In Profibus Dp - Siemens SIMOTION Function Manual

Synchronizing SIMOTION devices with a higher-level bus cycle clock
3.1 General information about synchronizing a SIMOTION device with the bus cycle clock
The interfaces can be operated as either slave or master.
The following provides a description of cycle clock generation and the various synchronization
mechanisms.
3.1.1

Cycle clock generation and synchronization in PROFIBUS DP

Clock generation in PROFIBUS DP
It is necessary to distinguish between the following cases for clock generation in PROFIBUS
DP:
● Precisely one PROFIBUS DP interface is configured as DP slave and is operated
● In all other cases (e.g. if no PROFIBUS DP interface has been configured as DP slave, or
The figure below displays the cycle clock generating principle in PROFIBUS DP.
alternatively, configured
basic clock cycle
Higher-level bus cycle clock
Figure 3-1 Cycle clock generation in a SIMOTION device in PROFIBUS DP
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isochronously:
In this case, this interface supplies the basic cycle clock for the SIMOTION device.
– If a DP cycle is available at this interface, the SIMOTION device must be synchronized
with this cycle clock. The synchronization behavior depends on whether the PROFIBUS
DP interfaces of the SIMOTION device have been configured as the isochronous DP
master. See the following section, "Synchronization in PROFIBUS DP".
– If no DP cycle clock is available at this interface (e.g. if the associated DP master fails),
a replacement cycle clock of the same size is generated.
the interface configured as DP slave is not operated isochronously), the following applies:
The basic cycle clock is derived from an internal cycle clock which is determined during
configuration (configured basic cycle clock).
Basic Functions for Modular Machines
Function Manual, 04/2014