ISA Watchdog Timer with Reset Pin Connector

Protect Your System Against Lockups with B&B's Watchdog Cards

B&B's Watchdog Timer cards are designed to overcome the dangers or annoyances associated with PCs locking up. PCs used in remote or dial-up applications, used for controlling external devices or performing data acquisition can all benefit from a watchdog. If the controlling software hangs or crashes, the watchdog will timeout and reboot the host machine (just like pressing the reset button). The application software must reset the card's counters every timeout period to prevent the watchdog from rebooting the computer - the reset commands are identical for each of the watchdog models. The timeout period is selected by writing four bits to a register, selectable from 0.5 seconds to over 500 seconds, and can be further extended with a minor modification. The read registers allow you to check the current status of the card. Each watchdog card has a SPDT Form C relay output with a rating of 115 VAC @ 0.5A, allowing an external alarm or other device to be controlled.

Model ATRWDT uses the ISA bus with any address from 0 to 3F8h, with no IRQ needed. It uses the motherboard reset pins to reboot when the computer locks up. A DB9 male connector is used for the relay connections. The 4-bit timeout register is read/write and contains a reset flag to identify if the computer's last reset was due to a watchdog timeout. The Form C relay can be configured as normally energized or normally discharged to fit into any application. A non-splicing connection wire is provided to make the connection from the ATRWDT to the motherboard's reset pins. Works under DOS, Windows 9x and Windows NT. Sample code is included.