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 PCWDT - B&B's original Watchdog Timer. The PCWDT is an ISA card which can be configured with any address from 0 to 3F8h, with no IRQ needed. This model uses a DB25 connector for external connections and includes a non-splicing connection wire to make the connection from the PCWDT to the motherboard's reset pins. A 4-bit write only register is used to set the timeout period. An isolated input is provided for resetting the card's counters with an external signal instead of using a software trigger. Works under DOS, Windows 9x and Windows NT. Sample code is included.