Hitachi CE50-10, Instruction Manual

Page: 118 / 194

5.16 Watchdog timer
Watchdog timer ( WDT ) is a function that monitors the execution times of the OS and processes. If one of the
execution times exceeds its predefined time limit (timeout), WDT interprets it as a fault and restarts the unit. A
function that monitors whether the OS is properly working is called a
hardware WDT . A function that monitors
whether the system daemon and application program processes are properly working is called a software WDT .
Figure 5‒28: Operation states of the unit and when the hardware WDT and software WDT are active
The following shows the interfaces used for operating the hardware WDT and software WDT.
Table 5‒20: WDT operations and interfaces
Classification Operation details Interface name
Hardware WDT Temporarily stop and restart operation. wdtctl command
Display the operation status. wdtstat command
Forcibly restart the unit. force_restart command
force_restart
library
Software WDT Start and stop.
swdt.conf
definition file
Temporarily stop the operation.
swdt_stop
command
Restart the temporarily stopped operation.
swdt_start
command
5. Configuring Software Environment
102