Dual Watchdog Operation - ICP DAS USA I-7021 User Manual

A.2 Dual Watchdog Operation
Dual Watchdog = Module Watchdog + Host Watchdog
The Module Watchdog is a hardware reset circuit that
monitors the operating status of the module. While
working in harsh or noisy environments, the module may
be shut down by external signals. The circuit allows the
module to work continuously without disruption.
The Host Watchdog is a software function that monitors
the operating status of the host. Its purpose is to prevent
problems due to network/communication errors or host
malfunctions. When a host watchdog timeout occurs, the
module will reset all outputs to a safe state in order to
prevent any erroneous operations of the controlled target.
I-7000 and M-7000 series modules include an internal
Dual Watchdog, making the control system more reliable
and stable.
For more information regarding the Dual Watchdog,
please refer to Chapter 5 of the "Getting Started For
I-7000 Series Modules" manual that can be downloaded
from the ICP DAS website http://www.icpdas.com.
I-7021/22/24, M-7022/24/28 User Manual, Rev: B2.3 179