Plc Status Register; Modbus Watchdog; Figure 108: State Diagram, Standard_Watchdog Operation Mode - WAGO 750-8207 Manual

WAGO-I/O-SYSTEM 750
750-8207 PFC200 CS 2ETH RS 3G
10.5.3

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.
10.5.4

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 108: State Diagram, STANDARD_WATCHDOG Operation Mode

Draft version 1.2.1 from 2017-09-13, valid from FW Version 02.06.20(09)
MODBUS – CODESYS 2 295
Manual