Using SSI encoder

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:

• No absolute encoder information is utilized, motor still needs to do Phasing a.k.a. phase search and Homing to get absolute operation.

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 [MT] 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 Motor typeMT 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.

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
GND	GND	10
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
CLK	GPI3	11
CSn	GPI2	12
DO	GPI1	13

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

Configuration

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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