Introduction

CPU or system errors are related either to the CPU (equipment or software) or to the rack internal bus wiring. The system can no longer operate correctly when these errors occur.

A CPU or system error causes the CPU to stop in ERROR mode and requires a cold restart. Before applying a cold restart, set the CPU to STOP mode to keep the PAC from returning to ERROR mode.

Diagnostics

A CPU or system error is diagnosed with the following indications:

• CPU I/O LED pattern: steady on

• system word %SW124 value defines the detected error source:

  • 80 hex: system watchdog error or rack internal bus wiring error

  • 81 hex: rack internal bus wiring error

  • 90 hex: interruption not foreseen, or system task pile overrun