Modbus Watchdog; Figure 112: State Diagram, Advanced_Watchdog Operation Mode - WAGO 750-8207 Manual

WAGO-I/O-SYSTEM 750
750-8207 PFC200 CS 2ETH RS 3G
11.2.1

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"). Exceptions here are the
Explicit Trigger mode and the access to the register 0xFA02 (Watchdog Status),
which can be configured via the register 0xFA03 (Watchdog Config).
The "Watchdog Timeout" response is initiated if no trigger occurs within the
timeout set in the register 0xFA01 (Watchdog Timeout) with the watchdog
running. The closing of all MODBUS TCP connections can be configured as a
response, see register 0xFA03 (Watchdog Config).
The MODBUS watchdog supports two different operation modes
ADVANCED_WATCHDOG and SIMPLE_WATCHDOG. The operation mode can
be selected via Bit 7 in the register 0xFA03 (Watchdog Config).
The following diagrams show the possible states of the MODBUS watchdog and
status transitions for the particular operation mode.

Figure 112: State Diagram, ADVANCED_WATCHDOG Operation Mode

Draft version 1.2.1 from 2017-09-13, valid from FW Version 02.06.20(09)
MODBUS – e!RUNTIME 309
Manual