WAGO-I/O-SYSTEM 750
Run-time System CODESYS 2.3 261
750-8207 PFC200 CS 2ETH RS 3G
Manual
Draft version 1.2.1 from 2017-09-13, valid from FW Version 02.06.20(09)
Table 199: Internal Data Bus Settings
Parameter
Explanation
Update Mode
The Update mode is used to configure how the internal data bus
process data is to be updated (refreshed).
Asynchronous In the asynchronous update mode process data
are refreshed in cycles at a definable interval.
Synchronous
*
In the synchronous update mode the process
data are synchronized with the most rapid
CODESYS task that accesses the internal data
bus.
Internal Data
Bus Cycle
Time
The update interval for the internal data bus is set by the cycle
time. This setting is effective only in the asynchronous mode.
1000 µs
Minimum value 1 millisecond
10000 µs
*
Default value 10 milliseconds
50000 µs
Maximum value 50 milliseconds
Internal Data
Bus Thread
Priority
This value indicates the priority for the internal data bus thread.
This setting is effective only in the asynchronous mode.
This priority is equivalent to the priority of the cyclic CODESYS
tasks (see Section “Cyclic Tasks”).
This setting is effective only in the asynchronous mode.
0
*
Highest priority
15
Lowest priority
PLC stop
response
Specifies the response of the internal data bus outputs when the
PLC application stops.
Hold last value The output states are retained.
Set to zero
*
Outputs are set to zero.
*
Default setting
8.9.5.1 Effect of Update Mode on CODESYS Tasks
8.9.5.1.1 Asynchronous Update Mode
In the asynchronous update mode there is no direct influence on CODESYS task
behavior.
Internal data bus “freeze” on priority conflicts!
In the asynchronous update mode there is a risk of the internal data bus
“freezing”, as the internal data bus thread operates at the same priority as the
IEC tasks. The internal data bus thread must therefore use a priority higher than
that of the IEC task to prevent this from occurring.
