HEIDENHAIN PROFIBUS-DP (DPV0) - Manual (Page 41)

Encoder and Gateway functionality, DPV0
41
Octet 1 2
Bits 15-8 7-0
Data 2 15 -2 8 2 7 -2 0
Data_Exchange -16 bits
Table 17 Data exchange -16 bits
Configuration data:
Device class 1: D0hex 1 input data word, data consistency
Device class 2: F0hex 1 input data word, 1 output data word for
preset value, data consistency
5.5.2
Preset function
The preset function enables adaptation of the position value
from the encoder to a known mechanical reference point of
the system. The preset function sets the actual position of
the encoder to zero or to the selected preset value. The
preset value is written to the encoder as output data in the
Data_Exchange function. If scaling is used the preset function
shall be used after the scaling function, to ensure that the
preset value is entered in the current measuring unit. The
most significant bit (MSB) of the preset value controls the
preset function as follows:
Normal operating mode: MSB = 0 (bit 31, optionally bit 15)
The encoder will not change the preset value.
Activated mode: MSB = 1 (bit 31, optionally bit 15) With
MSB = 1, the encoder accepts the transferred value (bits 0 –
30) as a preset value in binary code. The encoder reads the
current position value and calculates an offset value from the
preset value and the read position value. The position value is
shifted by the calculated offset value. If the input position
value equals the preset value, the preset mode is terminated
and the MSB can be set to 0 by the master. The offset value
can be read with the diagnostic function and is securely
stored in case of a power interruption and is reloaded at each
start-up.
Note: The preset function should only be used at encoder
standstill.