Using SSI encoder

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Revision as of 22:11, 26 July 2018 by Tero K (Talk | contribs) (List of tested SSI encoders:)

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SSI (Synchronous Serial Interface) is a digital protocol used by many encoder feedback device manufacturers. IONI Pro servo drive supports SSI encoders starting from firmware version 1.6.1.

SSI support details

As SSI is loosely defined standard, drive's SSI support may not cover all possible variations of the protocol. The following characteristics are supported:

  • Read clock 1.5-2 MHz
  • Strectched first clock for slower encoders
  • Multiturn & singleturn readout
    • Multiturn resolution from 0-16 bits
    • Singleturn resolution 4-32 bits
    • Sum of MT+ST resolutions must be between 4 and 32 bits
  • Binary and Gray code support

Current firmware version limitations:

List of tested SSI encoders:

Manufacturer Model Notes Test result
AMS AS5311 12 bit magnetic encoders All OK
RLS Orbis BR10SCB14B12BD00 14 bits absolute All OK
SICK TTK70-AXA0-K02 24 bits absolute, gray code All OK
Kübler 8.F3663.4121.G322 12 bit multiturn, 13 bit single turn, gray code All OK
Zettlex INC-4-100-211001-SSI2-RFC6-5-AN 21 bit singleturn, Zettlex's "SSI2" format Ok with workaround (use [FBMT] parameter as described below).

Zettlex encoders have uncommon SSI data formats with leading zeroes or status bits while GraniteCore drives assumes SSI data to begin with position information. Use Multi-turn bitsFBMT to skip those non-position info bits if necessary, and in such case keep Apply absolute position readingHAP disabled. However, if possible, choose Zettlex's SSI3, SSI5 or SSI8 formats which output position data bits first.

Zettlex INC-3-75-211001-SSI1-RFC9-12-AN and INC-4-37.080-171001-SSI1-RC371-12-S Zettlex's "SSI1" format

If you have tested another kind of encoder, please help us to inform the community by letting us know your encoder model and result by dropping a message into Granite Devices support.

Wiring SSI encoder

Wiring of SSI depends on the variant of SSI protocol present.

SSI encoder

Typical SSI encoder has differential signal lines and a supply voltage lines:

  • Power supply lines (2 wires)
  • Clock input (2 wires)
  • Data output (2 wires)

Connection to IONI Pro drive by following table:

BiSS wire IONI drive pin IONICUBE D-Sub 15 pin number Remarks
Cable shield Connector shell
5V input 9 Pin 9 is 5V supply output from IONICUBE to encoder
Clock+ GPI2 12
Clock- GPI3 11
Data+ C+ 15
Data- C- 14

AMS SSI encoder chips

AMS SSI encoders are wired following way to IONI encoder connector:

AMS wire IONI drive pin IONICUBE D-Sub 15 pin number Remarks
VSS (Ground) GND 10
VDD5V (5V input) 9 Pin 9 is 5V supply output from IONICUBE to encoder
CSn GPI2 12
DO GPI1 13

Refer to IONI & IONICUBE user guide for more info on wiring encoders.


SSI parameters in Granity. Example settings for AMS AS5311.

To configure SSI, use Granity version 1.11.1 or later. Configuration steps:

  1. Find out encoder MT and ST resolutions from encoder manufacturer's data sheet
  2. Select Serial data encoder from Feedback deviceFBD
  3. Select SSI type from Serial encoder typeFBS
  4. Set number of MT and ST bits into parameters Single-turn bitsFBST and Multi-turn bitsFBMT. If MT not specified in encoder data sheet, set it zero.

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