Installation Guide

10 Introduction
Hardware
Watchdog
Main
Processor
Measurement
Processor
System Health Monitor
System
Health
Monitor
Peripheral
Monitor
USB Power/Data
I/O Toggle
Serial
Reset Reset
Keep Alive
USB Hub
USB Power/Data
Peripheral
Figure 5. Watchdog Functions
System Watchdog and Reset
A dedicated processor provides hardware watchdog functionality for the entire
ECN system. The watchdog has master reset control over both the ECN main
system processor and the measurement processor.
The measurement processor maintains the watchdog with a 1.6 second refresh
signal. If the measurement processor fails to provide this signal, the hardware
watchdog automatically initiates a system reset. A system reset all processors,
USB hubs, communications devices, and expansion cards to causes reinitialize.
Measurement Processor Watchdog
The ECN measurement processor runs a software process to maintain a software
watchdog for the processor. If there is a malfunction of the measurement
scheduler, the software watchdog initiates a reset or a power cycle of the
processor, which causes a full system reset or power cycle for the ECN unit.
System Processor Watchdog
The ECN main system processor runs a process to maintain a software watchdog
for the processor. If there is a malfunction, the software watchdog initiates a
reset or a power cycle of the processor, which also causes all expansion cards to
be reset or power cycled.
Expansion Card Watchdog and Power Control
The ECN main system processor has power control over all peripherals, including
USB hubs and expansion slots. Applications running on the main system