HEIDENHAIN TNC 335 Technical Manual - Manual (Page 160)

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TNC 360 3 Servo Positioning of the NC Axes 4-63
3.3 Offset adjustment
The TNC 360/TNC 335 controls include several possibilities for compensating for an offset voltage
which would cause the axes to drift. The maximum permissible offset voltage in the control is
100 mV. If this voltage is reached or exceeded, then the error message
"Gross positioning error E"
will appear.
The automatic cyclical offset adjustment and the adjustment via integral factor must not be active
simultaneously!
3.3.1 Offset adjustment by code number
An automatic offset adjustment can be activated with the code number 75 368. After entering the
code number the control shows the offset values for the axes X, Y, Z, IV, in the dialog line. The
values indicate the voltage in 0.6 mV units. Thus a display of 10 means 10 x 0.6 mV = 6.0 mV. The
display 0 means no offset. The displayed offset value consists of the offset values that originate in
the motor controller and in the control.
On pressing the "ENT" key the offset values, which are displayed on the VDU, are automatically
compensated, the control puts out an appropriate compensating voltage. Compensation only takes
place if the offset voltage is > 0.6 mV.
To switch off the automatic offset adjustment, enter the code number and press the "NO ENT" key.
The offset values are stored in the control and are non-volatile.
After a control is exchanged, the offset adjustment must be re-activated via code number.
3.3.2 Automatic cyclical offset adjustment
The machine parameter MP1220 can be used to program a time interval, after which an offset
adjustment will be performed cyclically.
An automatic adjustment will be carried out, when the predetermined time has elapsed and the
following conditions are fulfilled:
- all axes are stopped,
- the spindle is not switched on,
the axes are not clamped.
For each adjustment cycle there will be a 1 mV correction if the offset voltage is larger than 1 mV. If
the offset voltage is smaller than 1 mV then compensation will be in steps of 0.6 mV.
MP1220 Automatic cyclical offset adjustment
Input value: 0 to 65536 [s]
0 = no automatic adjustment