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Encoder channels Ch1 to Ch3 each feature their own encoder gearing, while
encoder channel Ch4 (virtual encoders) does not feature
any encoder gearing.
In the case of encoder channel Ch2, it is assumed that the resolver will always be
used as a commutation encoder on the motor shaft. Because of this, the numerator
adjustment range is limited to a value of (+1) or (-1), while the denominator is set at a
fixed value of (+1), for the Ch2 encoder gearing ratio. This means that the only
option available is to invert the encoder signal (direction reversal).
As a whole, the encoder gearing is a scaling factor in the encoder evaluation system
and consists of numerator N (ENC_CHx_Num) for the motor side and denominator D
(ENC_CHx_Denom) for the encoder side (output side).
The following are used to configure the encoder gearing...

Ch1 with
P 510[0] - ENC_CH1_Num
and
P 511[0] - ENC_CH1_Denom
,

Ch2 with
P 512[0] - ENC_CH2_Num
and
P 513[0] - ENC_CH2_Denom
,

Ch3 with
P 514[0] - ENC_CH3_Num
and
P 515[0] - ENC_CH3_Denom
,
P No. Index Name Unit Description
510 0 ENC_CH1_Num Denominator of channel 1
511 0 ENC_CH1_Denom Numerator of channel 1
512 0 ENC_CH2_Num Denominator of channel 2
513 0 ENC_CH2_Denom Numerator of channel 2
514 0 ENC_CH3_Num Denominator of channel 3
515 0 ENC_CH3_Denom Numerator of channel 3
Table 6.14: Parameters for encoder gearing
MOOG
ID No.: CB40859-001 Date: 02/2018
MSD Servo Drive - Device Help
69
6 Encoder
Parameters

P 500[0] - ENC_CH1_ActVal[0].SingleTurn
and

P 500[1] - ENC_CH1_ActVal[1].MultiTurn
are used, for example, to indicate the current position value at the output for encoder
channel Ch1. These parameters can also be used for checking purposes during
commissioning.
NOTE

This value at the encoder channel output...
o
Already contains the encoder gearing ratio factor (N/D)
o
Will be passed this way through the system (incl. the
gearing gear ratio already)
o
I.e. is “the value” from the encoder evaluation system
The encoder gearing ratio has a multiplicative effect on the position progress, i.e.
either “expanding” or “compressing”.
A distinction can be drawn between an encoder’s motor mode and field mode:

Motor mode: The encoder is the motor commutation encoder

Field encoder: The encoder is
not
the motor commutation encoder (instead, it
is an additional encoder in the “field”, e.g. used for position control purposes)
In motor mode, the encoder gearing is used exclusively to synchronize the motor
shaft with the encoder shaft (default: 1:1 if the shaft is the same). In this case, a
position progress value will be passed to the system at the encoder channel output.
This value will be proportional to the position progress of the motor’s commutation
(adjusted for the pole pair number).
In field mode, the encoder gearing can be used “freely” for scaling purposes.