Siemens 27000/27100 alarm: Axis must be referenced

Sinumerik reports that the axis needs homing/referencing before operating. It is an alarm from the Sobrecarrera area, and in the catalog it is listed as “Axis must be referenced”. On the machine you notice it like this: It doesn't let you enter automatic, Ask to reference specific axis, Appears after starting or servo alarm.

On the shop floor it almost always comes from one of these causes: Axis not referenced after power-up, Reference loss, Absolute system required and battery/encoder affected. Rule out the most likely one on your machine first, before touching parameters or swapping anything.

Reset and complete a safe reference run. Resetting without fixing the cause first only hides the problem: Siemens 27000/27100 trips again and, in the meantime, you keep working with the machine in bad shape.

With the machine stopped and in a safe state, start with these checks: Note the pending axis, Comprobar recorrido libre, Referencing with low feed. That alone will tell you whether it is the program or whether you need to raise a maintenance job.

With Siemens 27000/27100 active, avoid this: Do not start machining without reference, Do not skip the homing sequence. Skipping any of these points is what turns a minor stop into an expensive breakdown.

If it does not establish the reference or loses it after every power-down. If you are not sure how far it goes, stop the machine and report it: a repeat alarm always works out cheaper than a crash.

It is a stop alarm: the cycle will not continue until you fix the cause. It does not always mean serious damage, but it leaves the machine where it is and you have to check it before running again. Guidance reference. Always confirm the full text in the exact machine/control manual.