Documentation Number PCWDT2901 - pg. 1/2
B&B Electronics Revised September 2001
This product designed and manufactured in USA of domestic and imported parts by
PC Watchdog Timer Card
CE
Model PCWDT
Introduction
B&B Electronics' PC Watchdog Timer Card, Model PCWDT, is a hardware
device designed to overcome the dangers or annoyances associated with a PC
"locking up." The PCWDT is periodically reset by your software or an external
hardware trigger. If the watchdog doesn't receive the reset trigger within a software
selectable timeout period, the PCWDT will "push" the reset button of the computer.
A form C relay output is also provided to reset an external device if desired.
Features
Software selectable timeout period from 0.5 to 550 seconds.
Range can be increased with a simple hardware modification.
Software enable and disable.
Form C relay output to control external device.
Non-splicing connection to motherboard reset pins.
Isolated timer reset input, for use as alternate trigger source.
Specifications
Dimensions:
2.6" H x 4.1" L
Address:
Occupies 1 byte of address space, selectable from 0 to 3F8h
Power:
250 mW maximum
Input specs:
Optically isolated input, requires 5 - 12 volts.
50
s minimum pulse width
Output specs: Form C relay, SPDT output, maximum ratings
24 VDC at 1.0 A
115 VAC at 0.5 A
Connector: DB25
male
Connections
In order for the PCWDT to reboot the host computer, a connection must be made in parallel with the reset switch to
the reset pins on the motherboard. A jumper wire is provided with the PCWDT to make this connection. Note that some
PCs do not include these pins on the motherboard. An additional input and output connection can be made through the
DB25 connector. A form C relay output is provided for connection to an external alarm or to shut down another device. An
isolated input is also provided to allow an external device to control the PCWDT.
Operation
The PCWDT works as a countdown timer that can be programmed to start its countdown from 0.5 seconds up to 550
seconds. A simple command, such as an OUT statement in Basic, must be added to a loop in the host computers
software. Every time this statement is executed, the timer is reset to its maximum value and restarts its countdown (an
external hardware trigger can also perform this function). If the code quits executing for any reason, the counter will
countdown until zero is reached, rebooting the host computer and energizing the output relay.
Documentation Number PCWDT2901 - pg. 2/2
B&B Electronics Revised September 2001
This product designed and manufactured in USA of domestic and imported parts by
B&B's Watchdog Family Selection Guide
Model
Bus
Timeout Register
Operating System
Output Relay Connecter
Reboot Connector
ATRWDT
ISA
4-bit, read-write, 1-bit reset flag
DOS, Win 9x, Windows NT
DB9 Male
Motherboard reset pins
ATXWDT
ISA
4-bit, read-write
DOS, Win 9x, Windows NT
DB9 Male
ATX Power Supply Connector
PCWDT
ISA
4-bit, write only
DOS, Win 9x, Windows NT
DB25 Male
Motherboard reset pins
PCIRWDT
PCI
4-bit, read-write, 1-bit reset flag
Windows 98/2000/ME/NT
DB9 Male
Motherboard reset pins
PCIXWDT
PCI
4-bit, read-write
Windows 98/2000/ME/NT
DB9 Male
ATX Power Supply Connector
DECLARATION OF CONFORMITY
Manufacturer's Name:
B&B Electronics Manufacturing Company
Manufacturer's Address:
P.O. Box 1040
707 Dayton Road
Ottawa, IL 61350 USA
Model Numbers:
PCWDT
Description:
PC Watchdog Timer Card
Type:
Light industrial ITE equipment
Application of Council Directive:
89/336/EEC
Standards: EN
50082-1:1998
EN 50082-1:1992 IEC 801 (-2, -3, -4)
EN 61000 (-4-2, -4-3, -4-4, -4-6)
Michael J. Fahrion, Director of Engineering
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