Beckhoff EL6692 Documentation page 123

Topology
Fig. 158: Topology of the example program
Station Master: EK1100, EL2202, EL6692
Station Slave: EK1100, EL2202
In this example, the EL6692 is synchronized in the direction PrimarySide --> SecondarySide (RJ45
connection). Synchronization in the other direction is also possible.
EL6692 documentation
Please note the information in the EL6692 documentation regarding the system behavior of this ter-
minal.
Demo program
In this demo program, the slave's own local DC time from the ReferenceClock in the EtherCAT strand is
offset by the time difference to the external synchronization device. This offset therefore only makes sense
on a platform that is a synchronization slave to one master.
The synchronization route can be
- another EtherCAT system; means: Beckhoff EL6692 bridge terminal (this example)
- an IEEE1588 system; means: Beckhoff EL6688 PTP terminal
- an arbitrary timer with time information (GPS, radio clock); means: TwinCAT 'External Synchronization'
supplement
The principle:
TwinCAT cyclically receives (e.g. every second) a pair (64-bit, unit 1 ns) made up of an internal (DC) and an
external time stamp. These two time stamps are originally obtained simultaneously. The offset between the
two timebases is calculated from the initial difference and made known in the System Manager | EtherCAT
device | InfoData. Furthermore, the slave TwinCAT readjusts its own local DC time from the course of the
two time stamps with respect to each other.
Calculations:
• current control deviation = DcToExtOffset – (external time stamp – internal time stamp)
This value ('signed', 64-bit) is compared to an application-specific limit; the validity of the time is output
if within the limit
• local synchronized time = local DC time + DcToExtOffset
This 'nuLocalTime' ('unsigned', 64-bit) can now be used for data logging and events with a time
reference to the master PC clock.
Setting up TwinCAT 2.11
In the following procedure the complete system is set up as follows:
• EL6692 primary side (E-bus): Sync Master (i.e. reference clock)
• EL6692 secondary side (RJ45 sockets): Sync Slave (i.e. synchronized side)
The synchronization direction of the time can be set up the other way around; the instructions must then be
followed analogously.
EL6692 Version: 3.2
Commissioning
123