treated as rotary SSI encoders (in this case, it is impossible to determine that
the system is a linear encoder system based on the encoder head). Likewise,
linear Sin/Cos encoders without an absolute value interface are treated as
“rotary” encoders (if run as commutation encoders, the number of tracks, or
lines (
Lines
) and the encoder gearing (
Num, Denom
) must be used to
establish the relationship to the linear motor’s magn. pole pair subdivision).
Only in the case of Sin/Cos encoders with distance-coded reference marks
will the system determine, based on
PeriodLen
> 0, that the encoder system
is linear and not rotary.
l
P 580[0] - ENC_CH3_Info
= Encoder Information
This parameter is available to the user so that they can enter a text of their
choice (max. 31 characters). This text should be used to describe the
encoder on channel Ch3
l
P 636[0] - ENC_CH3_CycleCount
= Sampling cycle in: n x 125 µs
(microseconds):
The CycleCount parameter can be used to slow down the timing for the
cyclical SSI encoder evaluation. By default, CycleCount = 1, i.e. the default
setting corresponds to 125 µs sampling and cycles for the encoder
evaluation. Different settings must be viewed as special cases and
accordingly must only be used when necessary. (see Section "SSI (cyclical)
X8" on page 87).
l
P 630[0] - ENC_CH3_NominalIncrementA
= distance coded absolute
encoder
P 631[0] - ENC_CH3_NominalIncrementB
= distance coded absolute
encoder
The NominalIncrementA and NominalIncrementB parameters make it
possible to run Sin/Cos incremental encoders (without an absolute value
interface) with analog distance-coded reference marks. E.g. If you were using
the Heidenhain ROD280C with 18000 Sin/Cos tracks per revolution and 36
distance-coded reference marks, you would need to set NominalIncrementA
to 1000 signal periods and NominalIncrementB to 1001 signal periods. This
functionality is enabled if NominalIncrementA > 0. (see Section "Increment-
coded reference marks" on page 105).
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P 637[0] - ENC_CH3_AbsInitMode
= Mode absolute value formation
AbsInitMode
can be used to select various possible settings for the absolute
MOOG
ID No.: CB40859-001 Date: 11/2020
MSD Servo Drive - Device Help
86
6 Encoder
value initialization:
o
DIG_ANA(0)- Standard:
Absolute value initialization using a mix of the digital and analog
components (this is the default mode)
o
DIG(1) - Digital:
Only the digital component will be used for the absolute value
initialization.
o
SEK_SEL37(2) - Automatic:
Digital if ST bits > (Li 8); otherwise standard
o
SSI_180(3) - Same as Standard, except:
In the case of SSI, the quadrant alignment of the digital value relative
to the analog Sin/Cos tracks is not the same as with EnDat, but is
instead offset by 180 degrees relative to EnDat, i.e. in the “natural Q
alignment” for the digital value relative to the tracks.
6.7.5.2.5 SSI absolute value interface
If P 570[0] - ENC_CH3_Abs = SSI(1), which is the normal setting, the absolute SSI
encoder position will be read once during the initialization phase; after this, the
cyclical encoder position will be acquired based on the Sin/Cos incremental
component.
The parameters for the SSI interface are described in Section "SSI (cyclical) X8" on
page 87, as are the differences in using the SSI interface with the “cyclical” method
and “one-time reading” method.
6.7.5.2.6 EnDat absolute value interface
If P 570[0] - ENC_CH3_Abs = ENDAT(2), the absolute EnDat encoder position will
be read once during the initialization phase; after this, the cyclical encoder position
will be acquired based on the Sin/Cos incremental component.
