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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 301717 - Axis drive SSI transmission timeout
Alarm 301717 indicates that the SSI (Synchronous Serial Interface) feedback transmission from the drive encoder cannot complete within a single NC clock cycle, typically 2ms on 840D systems. This timeout occurs when the SSI baud rate is too slow or the NC cycle time is too fast for the configured encoder data length and communication parameters.
301717
Siemens 301717 - Axis drive SSI transmission timeout
Axis drive SSI transmission timeout
The SSI transmission must be completed within an NC clock cycle. This is not possible with its current parameterization Control reaction: Mode group not ready. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm.
Root Cause Summary
Alarm 301717 indicates that the SSI (Synchronous Serial Interface) feedback transmission from the drive encoder cannot complete within a single NC clock cycle, typically 2ms on 840D systems. This timeout occurs when the SSI baud rate is too slow or the NC cycle time is too fast for the configured encoder data length and communication parameters.
Safety
- Drive/power/encoder circuit: hazardous voltages may remain in the DC link after power-off. Lock out / tag out, wait for discharge per the drive documentation, and use qualified personnel only.
Causes and Fixes
- 1
Access NCK parameters via Siemens HMI or SINUMERIK Operate: Navigate to Diagnosis > Parameters > Machine Data. Locate MD 34111 (SSI_BAUDRATE) for the affected axis.
- 2
Check current baud rate setting (typical values: 1000 kHz, 500 kHz). Compare against MD 34110 (SSI_DATA_LENGTH) - total bits required. Calculate: transmission_time = (SSI_DATA_LENGTH + overhead_bits) / baudrate_Hz.
- 3
Increase MD 34111 to maximum supported value (typically 1000 kHz or 2000 kHz depending on 840D version and hardware). Verify encoder and SSI interface support the higher baud rate per encoder documentation.
Increasing baud rate may introduce signal integrity issues on long cable runs. Use shielded twisted pair SSI cables and keep runs under 50 meters.
- 4
Save parameters and perform warm restart (NC Stop > Parameter Download > NC Start). Monitor alarm 301717 to confirm resolution.
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