To use the synchronization mode
Synchron with distributed clocks (DC)
, in your configu-
ration tool you have to select the synchronization mode
Synchron with DC-Sync0
. More
may be found in the manual of your configuration tool.
With this mode of synchronization, after receiving the EtherCAT frame, the process input
or output data is read or written in sync with the
DC sync event
. The
DC sync event
is an
interrupt which is triggered simultaneously on all DC capable slaves on the bus.
1
EtherCAT frame
2
DC sync event (DC Sync0)
3
Jitter, depends on the master implementation
In order to achieve isochronous mode, the synchronization mode Syn-
chronous with distributed clocks (DC) does not perform any hardware
retries on the backplane bus with process data telegrams. If errors are
detected when reading or writing the process data on the backplane bus,
the slave does not switch to PreOp. A module failure is detected by the
NodeMonitoring.
With the synchronization mode Synchron with distributed clocks (DC), no
System SLIO CP 040 may exist on the backplane bus.
4.4 Accessing the System SLIO
4.4.1 General
Calculation formula of the max. required cycle time in
µ
s so that the coupler safely
switches to the state
Operational (Op)
:
Max. required cycle time (in
µ
s) = (1.83 * number of modules) + (0.33 *
S
of input and
output bytes) + 60
In the following you will find the description of accessing the following System SLIO areas
via EtherCAT:
n
I/O area in the master system
n
I/O area
n
Parameter data
n
Module information
n
Diagnostics data
Information concerning the allocation of these areas may be found in the description of
the corresponding System SLIO module.
4.4.2 Accessing the I/O area in the master system
The EtherCAT slave has a variable process data mapping. The process data are
assigned to individual PDO mapping objects from the object dictionary, which can be acti-
vated or deactivated as required. The following PDO mapping objects are available:
Synchron with distributed
clocks (DC)
Overview
VIPA System SLIO
Deployment
Accessing the System SLIO > Accessing the I/O area in the master system
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