WAGO-I/O-SYSTEM 750 XTR
Run-time System CODESYS 2.3 283
750-8212/040-010 PFC200 G2 2ETH M12 RS XTR
Manual
Version 1.0.0, valid from FW version 03.01.07(13)
8.9
Local Bus Synchronization
The local bus cycle and the CODESYS task cycle are optimally automatically
synchronized: This depends on the number of I/O modules connected and the
fastest CODESYS task cycle set in the fieldbus controller. The synchronization
cases described below can therefore take place.
In this section, CODESYS task denotes only tasks within CODESYS that contain
an access to the local bus. Tasks that do not access the local bus are not
synchronized in the same way as described below. For this, see section
“Creating Tasks.”
8.9.1
Case 1: CODESYS Task Interval Set Smaller than the Local
Bus Cycle
Execution of the CODESYS tasks is synchronized with the local bus cycle time.
The CODESYS task is processed in parallel to the local bus cycle. The
CODESYS task interval is extended to the local bus cycle time. This is necessary
so that each CODESYS task is started with new input data from the local bus and
the output values are also set at the module after each CODESYS task.
Figure 96: Local Bus Synchronization (Case 1)
CTI:
CODESYS Task Interval
CT:
CODESYS Task that accesses the I/O modules via the local bus
LBZ:
Local Bus Cycle
Example:
CODESYS task interval (CTI): 100 µs
Local bus cycle (LBZ): 2000 µs
Result:
Matching of the CODESYS task interval to the local bus cycle of 2000
µs.
