ICP DAS USA PDS-700 Series, Руководство пользователя

Страница: 142 / 191

PDS Series User Manual ( V1.4, Oct. 2009) ----- 142
8.23. Application Notes
Hot Watchdog Status
The Power On Reset or Module Watchdog Reset will return all output settings to
Power On Values. The Host Watchdog Timeout will return all output values to Safe
Values. Additionally, the status of the Host Watchdog, which can be read using the ~AA0
command, will be recorded as 04, and output commands will be ignored until the status is
cleared to 0 by using command ~AA1.
Dual Watchdog Operation
Dual Watchdog = Module Wa Host Watchdog
The Module Watchdog is a hardware reset circuit that is used to monitor the operating
status of the module. When working in harsh or noisy environments, the module may be
interrupted by external signals. The circuit can let the module reboot automatically and to
work continues without halt.
The Host Watchdog is a software function that is used to monitor the operating status
of the host. Its purpose is to keep PDS’s output in a safe state when there is network
communication problem or host PC halt. If the timeout interval expires, the module will
turn all outputs to the predefined Safe Value and prevent unexpected situation from
occurring.
The PDS series with Dual Watchdog will make the control system more reliable and
stable.