Siemens SINUMERIK 840Di Function Manual page 1479

Avoiding readjustments
In some special cases, for example, when a machine axis (built-on rotary axes) is removed
and then mounted again, readjustment is not necessary/desirable.
To avoid readjustment, zero must be parameterized as a serial number to be ignored for the
measuring system of the machine axis in question.
MD34232 $MA_EVERY_ENC_SERIAL_NUMBER = FALSE
If the NC now reads zero as the serial number, the encoder status is not reset and the serial
number indicated in the machine data is kept.
Example sequence of operation:
1. The NC reads the serial number of the absolute encoder for the measuring system of the
2. The absolute encoder is calibrated in the correct manner.
3. When the controller is powered up subsequently, the NC reads "zero" as the serial
4. When the controller is powered up, the NC again reads the serial number it read under
Reference Point Approach (R1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
machine axis in question and the serial number is not equal to zero.
number of the absolute encoder.
Serial number "zero" is ignored and the encoder status remains the same, that is
"Calibrated".
Item 1 and that is still indicated in the machine data. The encoder status continues to be
"Adjusted".
Note
PROFIBUS drives
Because not all drives connected via PROFIBUS-DP can supply the encoder serial
number in a timely manner when the controller is powered up and some of these drives
cannot supply the encoder serial number at all, unnecessary readjustments can be
avoided by permanently setting the range of the encoder serial numbers for PROFIBUS
drives to FALSE internally in the NC:
MD34232 $MA_EVERY_ENC_SERIAL_NUMBER = FALSE
Manual parameterization to TRUE has no effect.
2.6 Referencing with absolute value encoders
Detailed Description
2-39