ifm electronic RN7003 - Manual (Page 17)

UK
CANopen encoder
17
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� The offset value can be read with the diagnostic function
(object 6509h), is stored in a non-volatile memory and reloaded at each start-up�
Only use the preset function if the shaft is stationary�
Format of the preset value
Byte 3 2 1 0
Bit 31 - 24 23 - 16 15 - 8 7 - 0
Data 2 31 - 2 24 2 23 - 2 16 2 15 - 2 8 2 7 - 2 0
object 6003h - preset value
Calculation of the preset value 6.6.2
An offset value is calculated when the encoder receives the preset value, see the
set-up calculation below� The offset value is then used during runtime to shift the
current position to the required output position, see the runtime calculation below�
In the formulas below the current position is the absolute position of the en-
coder disk after the scaling function� The calculations are made with signed
values�
Set-up calculation: offset_value = preset_value - current_value
A previously set offset value is not included in the current position�
Runtime calculation: output_position = current_position + offset_value