The parameters for the EnDat interface are described in Section "EnDat
(cyclical)X7" on page 58, as are the differences in using the EnDat interface with the
“cyclical” method and “one-time reading” method.
NOTE
SpecialTTLencoderswithcommutationtrackscanberunon
encoderchannelCh3(X8)bysettingP 507[0] - ENC_CH3_Selto
TTL_COM(5).
6.7.6SSI(cyclical)X8
Ch3: SSI(2) - Cyclical SSI
The software versions required to run the SSI encoder interface are the standard
software versions for the MSD Servo Drive and MSDSingle-Axis Servo Drive
Compact.
NOTE
Pleasenote thelimitations thatapply whenrunningEnDatand
SSI encoders (see Section "Limiting for EnDat and SSI" on
page50).
SSI (Synchronous Serial Interface) is a digital encoder interface that is supported by
a large number of manufacturers. It is not standardized, meaning that manufacturers
are free to support the interface as they like. The pseudo-standard described below
has however been established for motor feedback interfaces. Moog supports this
version first and foremost.
The following table lists the parameters for cyclical SSI operation on encoder
channel Ch3. It also points out possible differences between the use of the SSI
interface with the “cyclical” method and “one-time reading” method when using
Sin/Cos encoders with an SSI absolute value interface.
MOOG
ID
No.: CB40859-001 Date: 02/2018
MSD Servo Drive- Device Help
85
6 Encoder
SSI encoder basics and requirements
The SSI interface on the MSD Servo Drive has been designed as an actual motor
feedback interface. Accordingly, the connected SSI encoder must meet the following
criteria:
Clockanddatainactivelevel=HIGH
Thecurrentpositionmustbeinternallystoredatthefirstfallingclockedge
Nolengthenedcalculationtime(infirstcycle)
Withthefirstrisingclockedge,theencodermustshiftthedatatothefirst
positionbittobetransmitted(MSB)
1Mbpsrate
Datacoding=BinaryorGray
Readingdataafterthedatabitsendispermissible
125µscycle(i.e.internalpositionrefreshrate≪125µs)
Monofloptime≥6µs
Datalinesdrivenwithlogic0duringmonofloptime
Noparitybit
Noerrorbitsorotherstatusbits
≤14MultiTurnbits