C-Axis Operation - HEIDENHAIN TNC 426 PB/M Technical Manual

Table of Contents

6.12.15 C-Axis Operation

December 2001

In C-axis operation, an axis and a spindle are driven alternately by the same

The axis and spindle can be operated as an analog or digital axis or spindle. It

is not important whether the digital spindle is controlled with an integral DSP.

The axis and spindle can each have their own position encoders. Because the

speed encoder is built into the motor, it measures both the axis and the

Assignment of encoder inputs and speed command outputs to the axis and

In MP110.x enter the position encoder input of the axis (if present).

In MP111.x enter the position encoder input of the spindle (if present).

Enter MP112.x = 0 for the axis (it uses the speed encoder of the spindle

In MP113.x enter the speed encoder input of the spindle.

Enter in MP121.x for the spindle and in MP120.x for the axis

the same speed command output.

Commissioning of the axis and the spindle:

The current and speed controllers are commissioned only for the spindle.

Note the differences in the machine parameters between spindles with and

without integral spindle DSP. (See "Current Controller (Only TNC 426 PB/M,

TNC 430 PA/M)" on page 6 – 213)

Enter MP2xxx.x = 0 in the corresponding machine parameters of the axis.

The position controllers must be commissioned separately for the axis and

The axis position controller should be commissioned in the gear range that

is actually used for positioning.

If possible, use the lowest gear range to ensure optimum control.

If you use only one position encoder for both the spindle and the axis, the axis

display keeps running while the spindle is in operation:

Before switching from the axis to the spindle, save the actual position value

of the axis with Module 9146. This ensures that the axis display remains at

the last value, even when the spindle is rotating.

Before switching from the spindle to the axis, recover the actual position

value of the axis with Module 9146.

If you save the actual position value with Module 9146 and then close the

position control loop, or if the position control loop is closed and the actual

position value is then saved with Module 9146, the error message Actual

position value saved <Axis> appears. The error message triggers an

emergency stop.