Applicable Systems
KTP700 Comfort
Symptoms
The HMI touchscreen is unresponsive or registers touches at incorrect locations. The operator cannot navigate menus or acknowledge alarms.
Possible Causes
- Touchscreen calibration drifted due to age or temperature changes
- Touch panel controller IC damaged by electrical surge
- Front overlay scratched, cracked, or delaminated affecting touch sensitivity
- Excessive noise or EMI affecting the touch controller signals
Troubleshooting Steps
- Step 1: Access the HMI calibration menu (usually during boot by pressing a specific corner)
Follow the on-screen prompts to touch each calibration target accurately - Step 2: Inspect the front overlay for physical damage, scratches, or contamination
Clean with a soft cloth and isopropyl alcohol; replace the overlay if cracked - Step 3: Check the touch panel ribbon cable connection inside the HMI housing
Reseat the cable ensuring the contacts are clean and fully inserted - Step 4: If the touch controller is damaged, replace the touch panel assembly
Use only the OEM-specified replacement to ensure connector compatibility
How to Reset
Reset: Power cycle the HMI after calibration. The touch function should resume immediately.
Common Replacement Parts
- Touch panel assembly: Resistive or capacitive, 7-inch (Match to HMI model number)
- Front overlay: Anti-glare PET film or glass (Verify touch technology before ordering)
Frequently Asked Questions
- Q: How often should I calibrate the touchscreen?
Calibrate at commissioning and after any firmware update. Recalibrate if touch drift is noticed during operation.
- Q: Can I use a stylus on a capacitive touch HMI?
Only with a conductive stylus. Standard plastic styli work on resistive touch panels but not capacitive ones.
- Q: How do I protect the screen?
Apply an OEM-approved screen protector film. Avoid sharp objects and clean only with approved solvents.
Source: OEM Technical Manual
Category: HMI