Plc Status Register; Modbus Watchdog; Figure 107: State Diagram, Standard_Watchdog Operation Mode - WAGO I/O SYSTEM 750 Manual

280 MODBUS – CODESYS 2
9.5.3

PLC Status Register

Register 0x1040 provides the status (state) that the controller is currently in.
Possible values:
1 = PLC running − PLC status is RUNNING.
2 = PLC stopped − PLC status is STOPPED.
9.5.4

MODBUS Watchdog

The MODBUS watchdog monitors in the MODBUS slave the ongoing MODBUS
communication with the MODBUS master. All valid MODBUS requests of a
MODBUS master from all the services supported by the MODBUS slave are
trigger events (see chapter "MODBUS Mapping"). This does not apply to the
Explicit Trigger mode and the access to the register 0x1101 (Watchdog Status),
which can be configured via the 0x1103 (Watchdog Config) register.
If no trigger occurs during the watchdog within the timeout time set in the 0x1102
register (Watchdog Timeout), the "Watchdog Timeout" response is initiated. The
closing of all MODBUS TCP connections can be configured as a response, see
register 0x1103 (Watchdog Config).
The MODBUS watchdog supports two different functions
STANDARD_WATCHDOG and ALTERNATIVE_WATCHDOG. The
operation mode can be selected via the register 0x1104 (Watchdog Operation
Mode).
The following diagrams show the possible states of the MODBUS watchdog and
status transitions for the particular operation mode.

Figure 107: State Diagram, STANDARD_WATCHDOG Operation Mode

750-8208 PFC200 CS 2ETH RS CAN DPM
Version 1.1.0, valid from FW Version 02.06.20(09)
WAGO-I/O-SYSTEM 750
Manual