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Appendix C. Modbus Application Notes
C.1. Dual Watchdog
The Dual Watchdog consists of Module Watchdog and Host Watchdog.
1.
The Module Watchdog
is
a built-in hardware circuit
that will reset the CPU
module if a failure occurs
in either the hardware or
the software. If the
application does not
refresh the watchdog timer
within 0.8 seconds, the
watchdog circuit will
initiate a reset of the CPU.
2.
The Host Watchdog
is a
software function that can
be used to monitor the
operating status of the
host. Its purpose is to
prevent network
communication problems
or a host failure. If the
Watchdog timeout interval
expires, the module will
return all outputs to a
predefined Safe value
(Refer to the Safe Value
application note), which
can prevent the controlled
target from unexpected
situation.
AO address 40557 of the OME-ET-7000/OME-PET-7000 Modbus register is the
address of the Host Watchdog timer, and will be stored in EEPROM. The WDT
function will be disabled if the value is set to less than 5 seconds.
Summary of Contents for OME-ET-7000 Series
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