B&B Electronics PC Watchdog Timer Card ATRWDT Bedienungsanleitung PDF herunterladen (Seite 8)

P104-WDG-CSM User Manual

P104-WDG-CSMA: Standard Watchdog with Advanced Computer Status Monitor

This model provides a fully programmable watchdog with open collector outputs that

can reset the computer. It contains all available I/O to monitor and control the health of the

computer. It additionally contains extra features such as external or remote reset isolated

input, fan speed detect and fan speed control, light sensor for security if enclosure is opened

and two extra analog inputs that could be used to measure humidity or battery power for

example. (See Chapter 5 for 40-pin connector.)

a. Two undedicated analog inputs, 0 to +5V, eight-bit conversion.

b. One remote reset isolated input, current limit

c. Fan drive, PWM, open collector.

d. Additional +5 volts through a resettable fuse (300mA at room temperature).

e. +12 volts through a resettable fuse (300mA at room temperature).

Computer Power Monitor

The three computer power supplies (+5V, +12V, and -12V) may be monitored by this full-

featured version of the card. If one or more of those voltages vary by more than +6%, two bits

of a Status Register indicate whether there is an overvoltage or an undervoltage. In addition,

an interrupt request can be generated.

Fan Speed Control

This feature is used in conjunction with the Computer Temperature Monitor to automatically

maintain internal temperature in the enclosure by control of the fan speed. The duty cycle of

the +12V fan power return (GND) is pulse-width modulated to speed up the fan when

temperature increases. If no current is detected or the duty cycle reaches 100 percent, an

interrupt occurs.

Security Light Sensor

This feature is used when notification of un-authorized opening of dark computer enclosure is

required. A photo (light) sensor on one corner of watchdog board is connected to a dedicated

input of the onboard 8 bit A/D converter which provides the means for a software read of the

measured light.

External Remote Reset Opto-Isolated Input

Opto-isolated input #2 may be enabled to generate a reset (logically ORed with the Push

Button Reset input and the watchdog timer circuit). At least 3V must be applied to the isolated

input to trigger a RESET. The isolated input will tolerate 18 volts reverse bias. This second

dedicated opto-isolated input is used to remotely trigger a reset in the system. The voltage

input range is even capable of using an RS-232 transition to trigger a reset. The Opto-isolated

input signals are available at the P1 connector. (see Chapter 5)

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B&B Electronics PC Watchdog Timer Card ATRWDT Bedienungsanleitung Seite 8