Bb-electronics PC Watchdog Timer Card ATRWDT Manual do Utilizador descarregar pdf (Página 12)

10 Documentation Number ATxWDT-1303

B&B Electronics Mfg Co – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104

B&B Electronics Ltd – Westlink Comm. Pk – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445

The four bit latch values are also readable. Reading these bits is

recommended to verify the presence and setup of the WDT. The

BASIC command INP <WDTaddress> is used to read from the

WDT. The top three bits are not used and can be masked out. In the

ATRWDTthefifthbitistheresetflag.Itwillbea1whenthe

ATRWDTresetsthecomputeranda0ifthecomputerhasnotbeen

reset by the ATRWDT. This bit will be cleared if the computer is

turned off or after the bit has been read. A small example program,

written in QuickBASIC can be found in Appendix B.

Table 4. Registers

Write Register Read Register

L0 L0

L1 L1

L2 L2

L3 L3

X Reset Flag FOR ATR

XFORATX

X = Don’t Care

Pinouts

Three pins of the male DB-9 connector are used for the WDT.

Pins 4 and 7 are the external device reset relay contacts. These are

non-polarized, normally open contacts, and pins 3 and 7 are for the

normally closed.

Figure 2 is a schematic of the output portion of the WDT.

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Bb-electronics PC Watchdog Timer Card ATRWDT Manual do Utilizador Página 12