Axis clamping and monitoring

To ensure high quality and accuracy in a machining process (milling, turning, erosion machining, etc.), the tool-carrying axis can by physically fixed by the drive brake. Mechanical axis clamping is commanded by synchronised M/H functions in the NC program and enabled in the PLC. This ensures that an axis is clamped before the next motion block is executed.

The status ‘clamped axis’ is effective at axis driver level and remains valid cross-channel until it is deselected, even with axis exchange operations.

While an axis is clamped, neither the interpolator nor an additional interface can command it to drive by command values. The monitor required here is enabled and disabled by the following NC command. If a clamped axis is to be moved, the error message P-ERR-70525:is output and the CNC changes to error state.

The monitoring status is modal and remains active even after NC program end or RESET.

Monitoring specific clamped axes:

#CLAMP MONITORING ON | OFF [ {AX=.. | AXNR=..} ] modal

AX=<axis_name>      Name of clamped axis to be monitored.

AXNR=<expr>           Logical number of the axis to be monitored, positive integer

Monitoring all clamped axes:


Programing Example


Axis clamping and monitoring

N010 X0 Y0 Z0 A0 B0 C0

N020 A[M300] C[M300] ;Mechanical clamping of axes A + C on

N030 #CLAMP MONITORING ON ALL ;Enable monitoring of axes A + C


N100 #CLAMP MONITORING OFF ALL ;Disable monitoring of axes A + C


N110 #CLAMP MONITORING ON [AX=A AX=C] ;Enable monitoring of axes A + C

N120 Y10

N130 X15

N140 #CLAMP MONITORING OFF [AX=A AX=C] ;Disable monitoring of axes A + C

N150 X10
N160 #CLAMP MONITORING ON [AXNR=4 AXNR=6] ;Enable monitoring of axes A + C

N120 Y20

N130 X25

N150 A[M301] C[M301] ;Release mechanical clamping of axes A + C

N140 #CLAMP MONITORING OFF [AXNR=4 AXNR=6] ;Disable monitoring of axes A + C


N999 M30



The command does not cause any mechanical axis clamping. Instead, it enables the monitor for unauthorised axis motions. With the function ‘Backward motion on path’, the monitor status is inverted accordingly.



Axis motions which are generated by active compensation functions in the axis driver (e.g. Cross compensation, Volumetric Compensation, etc.) are not monitored.

The monitoring status of an axis can be read by the ADS access..

Index group: 0x20300

Index offset: 0x10189 (axis 1)