WAGO-I/O-SYSTEM 750
MODBUS – CODESYS 2 279
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)
10.3.1 MODBUS Settings
The “MODBUS settings” group contains the following configuration parameters.
Table 202: MODBUS Settings
Parameters Explanation
PLC stop
behavior
Response of the MODBUS slave when the controller has halted
(controller in STOP state)
No data
exchange
No data exchange possible. MODBUS requests
will always be answered by the exception
response “ILLEGAL FUNCTION” (0x81).
Switch to
substitute
value
*
Data exchange possible. Substitute values (0)
are provided for MODBUS read requests and the
values accepted unchanged in the local
MODBUS process image for write requests,
without passing these on to the controller.
Hold last value Data exchange possible. The last frozen values
are provided for MODBUS read requests and the
values accepted unchanged in the MODBUS
process image for write requests, without passing
these on to the controller.
Fieldbus error
response
Response of the MODBUS slave to detected fieldbus errors
(interruption of communication).
No data
exchange
No data exchange possible.
Switch to
substitute
value
*
Data exchange possible. Substitute values (0)
are supplied from the MODBUS process image
for PLC read functions; for write access the
values are accepted unchanged in the MODBUS
process image without passing them on to the
MODBUS master.
Hold last value Data exchange possible. The previously frozen
values are supplied from the MODBUS process
image for PLC read functions; for write access
the values are accepted unchanged in the
MODBUS process image without passing them
on to the MODBUS master.
*
Default setting