Heidenhain 120 alarm: Axis reference required

The TNC needs to reference one or more axes before allowing movements or programs. It is an alarm from the Servo / ejes area, and in the catalog it is listed as “Axis reference required”. On the machine you notice it like this: It asks for a reference run, It does not allow the program to start after turning on.

On the shop floor it almost always comes from one of these causes: Normal power-up without homing, Reference loss, Encoder/scale not initialised. Rule out the most likely one on your machine first, before touching parameters or swapping anything.

Resolved by completing the reference run and confirming the axes are ready. Resetting without fixing the cause first only hides the problem: Heidenhain 120 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: Execute reference according to machine order, Remove obstacles, Comprobar eje indicado. That alone will tell you whether it is the program or whether you need to raise a maintenance job.

With Heidenhain 120 active, avoid this: Do not move quickly without checking the free zone, Do not skip the reference run if the control requires it. Skipping any of these points is what turns a minor stop into an expensive breakdown.

If it does not detect reference or changes the position after referencing. 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. The procedure depends on TNC and machine kinematics.