Code 20055: [Channel %1: ] Master spindle not present in JOG mode
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Master spindle not present in JOG mode 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
Parameters: %1 = Channel number Definitions: The displayed axis is to be traver sed as machine axis in JOG mode with revolutional feed, but no master spindle has been defined from which t he actual speed could have been derived. Reaction: Local alarm reaction. Interface signals are set. Alarm display. Remedy: Please inform the authorized personnel/service department. If the revolutional feed is also to be active in JOG mode, then a master spindle must be declared via the channel-specific MD20090 $MC_SPIND_DEF_MASTER_SPIND. In this case you have to open a screen in the PARAMETER operating area with the softkeys "SETTINGDATA" and "JOG DATA" and preselect the G function G95 there. The JOG feedrate can then be entered in [mm/rev]. (If 0 mm/rev is set as JOG feed, the control takes the value assigned in the axis-specific MD 32050 $MA_JOG_REV_VELO or in the case of rapid traverse overlay MD32040 $MA_JOG_REV_VELO_RAPID). The revolutional feed in JOG mode is deactivate d by changing the G function from G95 to G94. Program Continuation: Clear alarm with the Delete key or NC START.
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 20055 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.
Have a better solution?
Help the industrial community by sharing your repair experience for code 20055.
Need a searchable reference for more Siemens SINUMERIK 840D CNC manuals?
We structure equipment manuals into searchable code, title, cause, solution, safety note, and source-reference data. Send a PDF and example searched codes when you need public pages, private search, or structured exports.
Space reserved for Google AdSense / Industrial Affiliate Links
Monetization target for 2026