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Siemens SINUMERIK Controller
Communication · Intermediate · 30-120 minutes
Siemens 20109 - Error in communication with the digitizer: status code of com-circuit:
Alarm 20109 indicates a serial communication protocol error between the SINUMERIK 840D NCK and the connected digitizing unit, manifesting as framing errors, parity violations, or checksum failures in the status byte of the communication circuit. This typically stems from baud rate mismatches, corrupted serial handshake parameters, or physical layer degradation on the digitizer interface port.
20109
Siemens 20109 - Error in communication with the digitizer: status code of com-circuit:
Error in communication with the digitizer: status code of com-circuit
The circuit for serial communication with the digitizing unit signals a transmission error via its status byte (framing error, parity etc.) Control reaction: Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Alarms.
Root Cause Summary
Alarm 20109 indicates a serial communication protocol error between the SINUMERIK 840D NCK and the connected digitizing unit, manifesting as framing errors, parity violations, or checksum failures in the status byte of the communication circuit. This typically stems from baud rate mismatches, corrupted serial handshake parameters, or physical layer degradation on the digitizer interface port.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Access SINUMERIK HMI: Diagnostics → Parameter → Machine Data (MD). Navigate to MD20100 and MD20101 to verify NCK digitizer baud rate and serial protocol settings (typically 9600 baud, 8N1).
Do not modify MD parameters during active digitizing operations; halt NCK first.
- 2
Cross-reference digitizer unit documentation and hardware configuration to confirm matching baud rate, parity (None/Even/Odd), and stop bits. Most SINUMERIK digitizers default to 9600 baud, 8 data bits, no parity, 1 stop bit.
- 3
If mismatch detected, modify MD20100 (and MD20101 if applicable) to match digitizer hardware settings. Save parameters and perform a warm restart (RESET) via the NCK control panel.
Changing serial parameters requires PLC/NCK synchronization; verify via Diagnostics → Communication Status after restart.
- 4
Re-engage digitizer probe and execute a test digitizing cycle. Monitor Alarm/Diagnostics log for recurrence of alarm 20109.
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