What causes Siemens SINUMERIK alarm 101651?

Required machine data or parameter not configured for the requested function. Option bit not set in SINUMERIK to enable the required functionality. Program references a function or axis that has not been configured. Machine commissioning incomplete — required setup step was not performed. Configuration data cleared or lost due to a parameter reset or hardware change.

How do I fix Siemens SINUMERIK alarm 101651?

1. Read the full alarm message to identify what is missing (axis name, parameter number, function name). 2. Consult the SINUMERIK alarm manual for alarm 101651 for the specific configuration requirement. 3. Check the relevant machine data group and set the required parameter. 4. If a specific option is required, verify it is licensed and enabled in the SINUMERIK option settings. 5. Power cycle after making configuration changes to apply the new settings.

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Siemens SINUMERIK Controller

Program/G-code · Intermediate · 30-120 minutes

Alarm 101651

Siemens 840D 101651 - No access method defined.

Alarm 101651 occurs when the SINUMERIK system attempts to access data or a resource without a properly defined access method in the configuration. This typically relates to missing or incorrectly configured communication protocols, file access methods, or interface definitions in machine data or OPI/HMI settings.

Siemens SINUMERIKProgram/G-codeIntermediate30-120 minutes

101651

Siemens 840D 101651 - No access method defined.

No access method defined.

Root Cause Summary

Alarm 101651 occurs when the SINUMERIK system attempts to access data or a resource without a properly defined access method in the configuration. This typically relates to missing or incorrectly configured communication protocols, file access methods, or interface definitions in machine data or OPI/HMI settings.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Navigate to Commissioning > System Data > Communication and verify OPI access method settings are properly configured.
2
Check machine data MD11300 $MN_OPI_INTERFACE_MODE and ensure it contains a valid value (typically 1 for Ethernet/TCP-IP or appropriate protocol).
Document current MD values before making changes
3
Verify network connection settings in Startup > Network Configuration match physical hardware connections and protocol requirements.
4
Perform a power cycle (NCU Reset) after correcting configuration and verify alarm clears during system startup.
Ensure no machining operations are active before resetting NCU

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