ACT-408A-N270 User Manual
Page 129
NOTE:
The following discussion applies to DOS environment. IEI support is
contacted or the IEI website visited for specific drivers for more
sophisticated operating systems, e.g., Windows and Linux.
The Watchdog Timer is provided to ensure that standalone systems can always recover
from catastrophic conditions that cause the CPU to crash. This condition may have
occurred by external EMI or a software bug. When the CPU stops working correctly,
Watchdog Timer either performs a hardware reset (cold boot) or a Non-Maskable Interrupt
(NMI) to bring the system back to a known state.
A BIOS function call (INT 15H) is used to control the Watchdog Timer:
INT 15H:
AH – 6FH Sub-function:
AL – 2:
Sets the Watchdog Timer’s period.
BL:
Time-out value (Its unit-second is dependent on the item “Watchdog
Timer unit select” in CMOS setup).
Table D-1: AH-6FH Sub-function
Call sub-function 2 to set the time-out period of Watchdog Timer first. If the time-out value
is not zero, the Watchdog Timer starts counting down. While the timer value reaches zero,
the system resets. To ensure that this reset condition does not occur, calling sub-function
2 must periodically refresh the Watchdog Timer. However, the Watchdog timer is disabled
if the time-out value is set to zero.
A tolerance of at least 10% must be maintained to avoid unknown routines within the
operating system (DOS), such as disk I/O that can be very time-consuming.
Summary of Contents for ACT-408A-N270
Page 12: ...ACT 408A N270 User Manual Page 12 Chapter 1 1 Introduction...
Page 22: ...ACT 408A N270 User Manual Page 22 Figure 1 8 ACT 408A N270 Dimensions mm...
Page 23: ...ACT 408A N270 User Manual Page 23 Chapter 2 2 Installation...
Page 49: ...ACT 408A N270 User Manual Page 49 Chapter 3 3 RFID Reader...
Page 64: ...ACT 408A N270 User Manual Page 64 Chapter 4 4 System Maintenance...
Page 72: ...ACT 408A N270 User Manual Page 72 Chapter 5 5 BIOS...
Page 115: ...ACT 408A N270 User Manual Page 115 Appendix A A External Connector Pinouts...
Page 120: ...ACT 408A N270 User Manual Page 120 Appendix B B Safety Precautions...
Page 124: ...ACT 408A N270 User Manual Page 124 Appendix C C BIOS Configuration Options...
Page 128: ...ACT 408A N270 User Manual Page 128 Appendix D D Watchdog Timer...
Page 131: ...ACT 408A N270 User Manual Page 131 Appendix E E Hazardous Materials Disclosure...