What causes Siemens SINUMERIK alarm 4620?

Machine data was changed requiring acknowledgment or power cycle. System configuration change notification. Commissioning or service operation generated this notice. Axis or drive configuration change affecting machine data.

How do I fix Siemens SINUMERIK alarm 4620?

1. Read the complete notice text on the SINUMERIK screen. 2. If a power cycle is indicated, perform a controlled machine power off and restart. 3. If machine data backup is indicated, save the current machine data. 4. Acknowledge the notice and verify the system is operating correctly after the change. 5. Consult the machine commissioning engineer if the notice is unexpected.

axismd.ai

Siemens SINUMERIK Controller

System · Intermediate · 30-120 minutes

Alarm 4620

Siemens 840D 4620 - Invalid handwheel module for handwheel

Alarm 4620 fires when the machine data parameter $MN_HANDWHEEL_MODULE is configured with an invalid module number for a handwheel connected to an 802D control system. The 802D architecture treats the control itself as a single monolithic module (module 1), and any handwheel directly interfaced with 802D must reference this fixed module assignment, not alternative module numbers intended for 840D multi-module configurations.

Siemens SINUMERIKSystemIntermediate30-120 minutes

4620

Siemens 840D 4620 - Invalid handwheel module for handwheel

Invalid handwheel module for handwheel

Root Cause Summary

Alarm 4620 fires when the machine data parameter $MN_HANDWHEEL_MODULE is configured with an invalid module number for a handwheel connected to an 802D control system. The 802D architecture treats the control itself as a single monolithic module (module 1), and any handwheel directly interfaced with 802D must reference this fixed module assignment, not alternative module numbers intended for 840D multi-module configurations.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Access machine data via HMI or Siemens SINUMERIK Operate > Maintenance > Machine data > List 'HANDWHEEL'. Locate $MN_HANDWHEEL_MODULE and note the current value.
Do not modify while NC program is running or during active handwheel operations.
2
Verify control system type: Check hardware commissioning documentation or HMI system info screen. Confirm if control is 802D (single module) or 840D (multi-module capable). For 802D, this parameter must always equal 1.
3
Change $MN_HANDWHEEL_MODULE to 1 in machine data. Save changes and trigger a warm restart (Ctrl+Shift+Restart or NC Reset > System Reset).
Warm restart will interrupt any running programs. Perform during machine idle state only.
4
Test handwheel functionality through manual jog or handwheel enable switch. Verify alarm 4620 no longer appears in alarm list.

Service Recommended confidence

Seeing Multiple Alarms?

Seeing another alarm with this one? Enter the code.

Get machine-aware diagnosis

AxisMD logs alarms against your actual machines, tracks patterns, and gives AI context your manual doesn't have.

Start free

Was this guide helpful?

Always verify with your machine manual or a certified technician before performing service procedures.