Code 201943: <location>IF1: PB/PN clock cycle signal error when establishing bus communication
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>IF1: PB/PN clock cycle signal error when establishing bus communication alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Message value: Drive object: All objects Reaction: NONE Acknowledge: NONE Cause: The bus is in the data exchange state and clock synchronous operation has been selected using the parameterizing telegram. The global control telegram for synchronizati on is being irregularly received. -.the master is sending an irr egular global control telegram. - the master is using another clock synchronous DP clock cycle than was transf erred to the slave in the parameterizing telegram. SINAMICS-Alarms Remedy: - check the master application and bus configuration. - check the consistency between the clock cycle input when configuring the slave and clock cycle setting at the master. Note: IF1: Interface 1 PB: PROFIBUS PN: PROFINET
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 201943 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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