HEIDENHAIN TNC 306 Technical Manual - Manual (Page 144)

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TNC 406/TNC 306 3 Servo positioning of the NC-axes 3/97
3.3 Offset adjustment
The TNC includes several possibilities for compensating 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, the error message
"Gross positioning error E"
will appear.
3.3.1 Offset adjustment by code number
An automatic offset adjustment can be activated with the code number 75368. After entering the
code number the control shows the offset values for the axes X, Y, Z, 4, in the dialog line. The
values indicate the voltage in 0.15 mV (LE406) and 0.6 mV (LE360) units. Thus a display of 10 means
10 x 0.6 mV = 6.0 mV (LE360). The display 0 means no offset.
The displayed offset value is derived from the offsets in the drive amplifier and control system.
On pressing the "ENT" key the offset values which are displayed on the VDU are automatically
compensated. The control puts out a compensating voltage. The compensation only takes place if
the offset voltage is > 0.6 mV.
To switch off the 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 exchange the offset compensation via code number must be re-activated.
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,
- MO5 status active,
- 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 steps of 0.6 mV will be used .
MP1220 Automatic cyclical offset adjustment
Entry value: 0 to 65 535 [s]
0 = no automatic adjustment