Omron SYSMAC Error Code E04

Omron PLC & VFD Major System

Model: SYSMAC | Code: E04

Applicable Systems
CJ/CS Series

Symptoms

The SYSMAC reports a watchdog timeout fault. The system watchdog timer expired without receiving the expected communication or task completion signal.

Possible Causes

  • Host controller communication interrupted or stopped
  • Application task execution exceeded the watchdog timeout period
  • Watchdog timeout setting too short for the actual task cycle time

Troubleshooting Steps

  1. Step 1: Check the host controller communication link status in the drive
    Communication link is active and stable
  2. Step 2: Review the task execution time and compare with the watchdog setting
    Task completes within the watchdog period
  3. Step 3: Increase the watchdog timeout if the task legitimately requires more time
    Watchdog timeout accommodates the task cycle

How to Reset

To reset: Restore communication or fix the task timing, then reset.

Related Omron Fault Codes

Source: Omron CJ/CS Series PLC Programming Manual, Omron Corporation

Category: PLC & VFD