In industrial environments, when an HMI touch screen fails, an entire production line may come to a halt. As equipment maintenance personnel, quickly diagnosing the problem and minimizing downtime is your core competency.
Today, we’ll discuss the three most common HMI faults and how to troubleshoot them.
1. Black Screen or Display Artifacts
Possible causes:
- Backlight power failure
- LCD panel damage
- Loose or faulty connection cables
- High ambient temperature causing hardware damage
Troubleshooting steps:
- Check if the power indicator is lit—if not, check the 24V power supply
- Re-seat the communication cables between HMI and PLC, observe if the issue resolves
- Use a multimeter to measure backlight voltage
- Check ambient temperature—does it exceed the rated operating temperature (typically 0-50°C)?
Solution:
If hardware is damaged, replacing the HMI is the fastest solution. We recommend the Delta DOP-107BV series—7-inch touch screen, excellent compatibility, affordable price, supports RS232/RS485 communication, suitable for most small to medium equipment.
👉 Delta DOP-107BV 7" HMI Touch Screen
2. Unresponsive or Drifting Touch
Possible causes:
- Dirt or moisture on touch surface
- Touch controller calibration data lost
- Electromagnetic interference
- Aging touch panel hardware
Troubleshooting steps:
- Clean the screen surface, ensure no oil, water, or debris
- Enter HMI system settings and recalibrate the touch screen
- Check for strong electromagnetic interference sources nearby (variable frequency drives, high-power motors)
- If recalibration doesn’t work, consider hardware aging
Solution:
Older resistive touch screens are prone to drift over time. Consider upgrading to capacitive screens. The Delta DOP-107SV series features high-quality touch panels—responsive, sensitive, and longer lifespan.
3. Communication Failure (HMI Cannot Read PLC Data)
Possible causes:
- Incorrect communication parameters (baud rate, station number)
- Damaged or incorrectly wired communication cables
- PLC communication module failure
- Protocol mismatch
Troubleshooting steps:
- Verify HMI and PLC communication parameters match
- Check if communication cables are intact and properly wired
- Try connecting the PLC directly with a computer to verify PLC communication
- Confirm the HMI’s communication protocol matches the PLC model
Solution:
Communication cable quality directly affects stability. We provide matching communication cables with complete shielding, strong anti-interference capability, plug-and-play.
Final Thoughts
The core principle for HMI troubleshooting: software first, then hardware; external first, then internal. Check “soft” issues like parameter settings and wiring before considering hardware damage. Rule out external environmental factors before suspecting the device itself.
If hardware damage is confirmed, feel free to contact us. Wavetopauto specializes in industrial automation components—Delta, Mitsubishi, Omron, Panasonic HMI, PLC, and servo motors. Original quality, competitive prices, fast shipping.
📧 Email: wavetop-abbey@foxmail.com