A vertical machining center with Siemens 810M CNC control system, run L81 or L84 fixed circles under AUTO mode, the Z axis-return could not be defined by R10 parameter, but return to the R2 reference plane.

The other functions of the machine is fine, so the problem should come from the CNC software selection.

Fixed circle of Siemens 810M has UMS02 and UMS03 two basic forms, when the UMS02 is selected, then only L82, L83, L85 and other very few fixed circles can return to R10 plane, most of the fixed circles returns to the R2 plane.

UMS02 or UMS03 can be selected by setting the machine parameter SD5000 bit0, when the SD5000 bit0=0, the UMS02 is selected, when SD5000 bit0=1, then the USM03 is selected.

In this case we could set the SD5000 bit0=1, then all the fixed circles could return to R10 plane.