Scan Time Over - Watchdog Timer Error

Keyence PLC & VFD Critical PLC

Model: Keyence KV-3000 PLC | Code: KV-3000

Applicable Systems
KV-3000 KV-800 KV-700 KV Nano

Symptoms

PLC scan time exceeds watchdog timer setting; PLC enters STOP mode; all outputs turn OFF for safety.

Possible Causes

  • Program complexity exceeding CPU processing capacity
  • Excessive communication load on network
  • Infinite loop or recursion in user program

Troubleshooting Steps

  1. Step 1: Check scan time monitor in KV Builder software
    Scan time within watchdog setting
  2. Step 2: Review program for inefficient constructs or loops
    No unnecessary processing
  3. Step 3: Move non-time-critical logic to lower priority tasks
    Task priority optimized
  4. Step 4: Increase watchdog timer setting if needed (caution)
    Watchdog adjusted appropriately
  5. Step 5: Clear error and verify scan time stable
    Scan time stable

How to Reset

Clear via KV Builder: clear watchdog error, verify program stability.

Frequently Asked Questions

  • Q: What is KV Builder?

    Keyence's PLC programming software for KV series. Provides ladder programming, monitoring, and debugging for KV-3000, KV-800, and KV-700 PLCs.

Source: Keyence KV-3000 User Manual

Category: PLC & VFD