Rockwell-automation 2711P Software Development Kit User Manual Bedienungsanleitung PDF herunterladen (Seite 36)

Publication 2711P-UM005A-EN-P - March 2007

36 PanelView Plus CE-Specific Extensions to the WinCE API

Hardware Watchdog

Watchdog_Tag

The function combines the ability to enable or disable the hardware

watchdog, tag the watchdog and to optionally set a new timeout value

in the watchdog timer register. It is used in a separate thread within

the watchdog service DLL. Normally, this function would not be used

by an application (exe).

DWORD Watchdog_Tag(DWORD dwTimeout)

Parameters:

dwTimeout

• A value of 0 tags (restarts) the watchdog timer and leaves the

timeout unchanged.

• A value of MAXDWORD (0xFFFFFFFF) disables the watchdog.

• Any other value that is within the range of the timer (50 to

5000), enables the watchdog and sets the timeout in

milliseconds.

Return Values:

Remarks:

If the hardware watchdog is disabled, calling Watchdog_Tag(0) will

always return WATCHDOG_TIMEOUT_FAILED as no current

watchdog timeout value is defined.

If Watchdog_Tag() is called with a timeout value that is out of the

range of the timer then the timeout value currently being used by the

watchdog is left unmodified and WATCHDOG_TIMEOUT_FAILED is

returned. The range of the hardware watchdog timer is 50 to 5,000

milliseconds.

Portability:

Same as the 2711P.

Hardware Watchdog - Return Codes

Value Description

WATCHDOG_OK The Watchdog function was successful

WATCHDOG_NOT_PRESENT Communication with watchdog device failed

WATCHDOG_TIMEOUT_FAILED Watchdog was tagged, but the requested

timeout value was not set.

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Rockwell-automation 2711P Software Development Kit User Manual Bedienungsanleitung Seite 36