When the Screen Loses the Machine
If a "Connection Disconnected" or "PLC no communication" warning suddenly appears on Siemens Simatic or similar operator panels (HMI), the panel cannot talk to the PLC (the machine's brain). Even if there is a display, buttons won't work.
Main Causes of Communication Errors
- Cable and Socket Issues: Due to factory vibration, Profibus, MPI, or Profinet (Ethernet) communication cable sockets may have loosened, or the cable may have been crushed and broken internally.
- Burnt HMI Comm Port: Communication chips behind the screen may burn out due to factory grounding issues or voltage surges (noise). The screen works but cannot transmit data.
- PLC Stopped: The issue might not be the screen, but the PLC in the cabinet. If the PLC switches to STOP mode (red light) due to a software or hardware error, the screen cannot connect.
Code Elektronik On-Site HMI Service
Communication issues cannot be solved by trial and error. Our expert team visits the factory and uses network analyzers to determine exactly where data packets are lost. If the issue is the HMI hardware, port repairs are done in our lab.