Quick Checks
Before detailed troubleshooting, verify these basic items:
Communication Issues
PLC Connection Failed
Symptom: Status bar shows "PLC: Disconnected" (red)
Possible Causes:
- Network cable disconnected or faulty
- Wrong IP address configured
- PLC powered off or in STOP mode
- Firewall blocking port 502
Solutions:
- Ping the PLC IP address from command prompt
- Verify IP address in Settings > PLC Configuration
- Check PLC power and status LEDs
- Verify firewall allows port 502 (Modbus TCP)
- Check network switch and cables
Scanner Connection Failed
Symptom: Status bar shows "Scanner: Disconnected" (red)
Possible Causes:
- QCS system not responding
- Wrong IP address or port
- Modbus server not enabled on QCS
Solutions:
- Ping the QCS/scanner IP address
- Verify configuration in Settings > Scanner Configuration
- Check QCS system is operating normally
- Confirm Modbus TCP is enabled on QCS
Intermittent Connection
Symptom: Connection status fluctuates between connected and disconnected
Possible Causes:
- Network congestion or packet loss
- Faulty cable or connector
- Timeout settings too short
Solutions:
- Increase connection timeout to 5000ms
- Replace network cables
- Use dedicated industrial network
- Check for duplicate IP addresses
Control Issues
Profile Not Improving
Symptom: Zones in AUTO mode but profile deviation not decreasing
Possible Causes:
- Control gain too low
- Zone mapping incorrect
- Valves not responding
- Response matrix not configured
Solutions:
- Increase control gain gradually (0.3 → 0.5)
- Verify zone mapping matches physical layout
- Test valves in manual mode
- Check response matrix configuration
Oscillating Profile
Symptom: Profile swings back and forth, valves constantly moving
Possible Causes:
- Control gain too high
- Control interval too short
- Filter depth too low (noisy data)
Solutions:
- Reduce control gain (e.g., 0.5 → 0.3)
- Increase control interval (e.g., 60s → 90s)
- Increase filter depth (e.g., 0.2 → 0.4)
- Increase deadband setting
Zones Not Responding
Symptom: Setpoint changes but feedback doesn't follow
Possible Causes:
- Zone in MANUAL or LOCAL mode
- Valve stuck or faulty
- PLC not processing setpoints
- I/O module fault
Solutions:
- Verify zone is in AUTO mode
- Check valve manually at the headbox
- Monitor PLC program execution
- Check I/O module diagnostics
Profile Issues
Profile All Zeros
Symptom: Profile display shows flat line at zero
Solutions:
- Verify scanner is traversing (not parked)
- Check register addresses in scanner configuration
- Verify data type (Float vs Integer)
- Check "Profile Valid" flag from QCS
Profile Values Wrong
Symptom: Profile values are very large, very small, or negative when they shouldn't be
Solutions:
- Toggle byte order setting (Big/Little Endian)
- Toggle word order setting
- Verify data type matches QCS output
- Check scaling factor if using integers
Profile Inverted or Offset
Symptom: Profile appears mirrored or shifted from actual position
Solutions:
- Toggle mapping direction (Front-to-Back vs Back-to-Front)
- Adjust front/back side offsets
- Verify databox count matches QCS
Actuator Issues
Valve Not Moving
Check List:
- Verify pneumatic air supply is on
- Check I/P converter operation
- Verify analog output signal at PLC
- Inspect valve for mechanical binding
- Check feedback potentiometer
Feedback Mismatch
Symptom: Large difference between setpoint and feedback
Solutions:
- Calibrate valve feedback sensor
- Check for mechanical problems
- Verify feedback scaling in PLC
- Check feedback wiring
Getting Support
Contact PowerFlow
For technical support with the Dilution Control System:
- Email: [email protected]
- Subject: Dilution Control Support - [Your Company]
Information to Include:
- Company name and mill location
- Software version number
- Description of the problem
- Error messages (screenshots if possible)
- Steps already tried
- Configuration details (QCS type, PLC type)