Applicable Systems
CJ/CS Series
Symptoms
User-defined non-fatal error triggered by FALS instruction in ladder program; specific to application logic.
Possible Causes
- Application logic intentionally triggered error condition
- Process parameter out of acceptable range
- Sensor input reading outside programmed limits
Troubleshooting Steps
- Step 1: Check PLC error log via CX-Programmer for specific FALS number
FALS error number identifies specific logic block - Step 2: Review ladder program at FALS instruction location
Identify which condition triggered the error - Step 3: Verify process inputs that triggered the alarm
Inputs within normal range after investigation - Step 4: Clear error condition via CX-Programmer
Error cleared, process resumes - Step 5: If alarm recurs, modify alarm thresholds in logic
Alarm threshold adjusted appropriately
How to Reset
Clear via CX-Programmer: clear FALS error and reset error flag (A500.00-A500.15).
Frequently Asked Questions
- Q: What is FALS in Omron PLC?
Failure Alarm System. FALS instruction generates user-defined errors. FAL=non-fatal (continues running), FALS=fatal (stops PLC execution).
Source: Omron CJ2M Operation Manual W394
Category: PLC & VFD