Commissioning
EL1502, EL1512
117
Version: 3.5
Fig. 143: EL1502-0000-0021 – Standard scope of process data
5.5.1.3
Distributed Clocks (DC)
EtherCAT and Distributed Clocks
A basic introduction into EtherCAT and distributed clocks is available for download from the Beck-
hoff website: the “Distributed clocks system description”.
The EL1502 device supports the distributed clocks function. In order for the EL1502 to be able to make the
current counter value available in the designated process data in time before the arrival of the querying
EtherCAT datagram, a suitable signal must be generated cyclically within the terminal. This signal can be
triggered in the EL1502 through two events: the SyncManager (SM) and the distributed clock (DC). Under
operating mode selection the following options are available (see Fig.
"DC" (Disributed Clocks) tab
):
• SM Synchronous
The SynManager event occurs when an EtherCAT frame successfully exchanges process data with
the EL1502. Frame-triggered, the current counter value is thus cyclically determined, but with the low
temporal jitter of the Ethernet frame.