Contec SCP-8550-LLV, User Manual

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6. RAS Functions
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SCP-8550-LLV
Watch dog timer
The watchdog timer is started by output of A5 to I/O port address 4002h. A second output of A5 to the
same port within the specified expiration time once again triggers the watchdog timer. If a time-out
occurs, a reset or an interrupt is generated according to the 4004h port setting or an alarm is output
according to the 4004h port setting.
The time-out period can be set between 1 and 255 seconds depending on the timer value setting for the
WDT counter port (4003h).
The watchdog timer stops by reading port 4002h. The alarm-out output is cancelled at the same time.
The alarm out is output from the RAS connector's PO2/WDT (pin 12) and cancelled when reset.
The alarm-out output can be set to BIOS startup by BIOS setup (see Chapter8), watchdog timer startup,
or watchdog timer time-up.
Specifications
- Time to be set : 1sec - 255sec
- Interrupt or reset : Resets or generates an interrupt at time-up (Port setting).
- External alarm output : Photo-coupler insulated open-collector output (the output status is
set by software). For more information, see the general-purpose
I/O specifications.
- I/O addresses : 4001h - 4005h (WDT port)