Etel DSC2P - Page 87

ETEL Doc. - Operation & Software Manual # DSC2P 903 / Ver. F / 3/6/05 Chapter C: System functions
Operation & Software Manual
Direct Drives & Systems 87
The encoder resolution, which is the smallest distance measured by the encoder, is given by the following
formula:
Parameter K75 calculation, formula for rotary motors:
Offset correction (K70, K71):
If parameter K70 or/and K71 is smaller than 0, a positive offset is added to the corresponding signal and a value
higher than 0 adds a negative offset. If parameter K70 or/and K71 is equal to 0, no offset correction is done.
Remark: Monitorings M40 and M41 allows the user to monitor the sine and cosine signals of the analog
encoder (refer to §12.3.7
for more information).
Amplitude correction (K72, K73):
The amplitude correction only allows the decrease of the signal amplitude and never the increase of it. That is
why, the encoder head tuning is highly important because it will not be possible to correct a too weak
amplitude with the software. It is possible to decrease a signal amplitude at best by a factor 2 with the value
16384. The value 32767 does not correct any encoder signals amplitude.
Remark: During offset and amplitude corrections manual research, it is advised to start first disabling
individually every signal offset, and then to correct the amplitudes in order to adjust the bigger on
the smaller.
Analog encoder resolution [m]
Encoder period [m]
1024 2
K77
⋅
Interpolation factor
------------------------------------------
=
  
K75
1024 NPCod
⋅
NRef
-------------------------------
with NRef = nb. of encoder reference marks / turn=
Sensor amplitude
Signal without offset correction
K70 and K71 = 0
Signal with offset correction
K70, K71 between -1024 and 1024
bigger than 0 ⇒ move down
smaller than 0 ⇒ move up
Position
Sensor amplitude
Signal without amplitude correction
K72, K73 = 32767
Signal with amplitude correction
for adjusting, value is included
between 32767 (·1) and 16384 (·1/2)
A
A / 2
Position
Sensor amplitude
Signal without amplitude correction
K72, K73 = 32767
Signal with amplitude correction
for adjusting, value is included
between 32767 (·1) and 16384 (·1/2)
A
A / 2
Position