Servo Motors: Absolute Encoders & Drive Compatibility

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An absolute encoder is a rotary feedback device that retains position information even when powered off. Its main use is to eliminate the need to "home" the axis when powered on. They can be divided into two kinds: single-turn and multi-turn. Single-turn absolute encoders, like normal (incremental) encoders, can still measure long distances (typically millions of revolutions). The difference is that single-turn absolute encoders retain their orientation when turned off, and multi-turn absolute encoders retain their orientation AND the number of revolutions they have gone. Single-turn absolute encoders have the advantage of having much higher resolutions than incremental encoders. Since servo motors are error driven systems, this gives more feedback counts, allowing for easier tuning and more stability.  Multi-turn absolute encoders have the same resolution over any revolution as the single-turn allowing for similar stability.

There are many types of absolute position feedback devices. Sine-Cosine ("SinCos") encoders are one very common technology. Within this branch of absolute encoders, two appear on Parker motors. These are the Heidenhain EnDat and the Stegmann Hiperface.

BiSS-C is a synchronous serial absolute encoder which is a newer technology with high resolution and lower pricing. These are standard with the P series motors (PM-FAL / PM-FBL / PM-FCL rotary motors and the PM-DD direct drive rotary). The P series drives and IPA are compatible.

HyperfaceDSL is also a newer technology and uses only 2 conductors allowing single connector on the motor for both motor power and feedback. This is the new 6H option on the MPP/MPJ series servo motors. The IPA and PSD are compatible.

The Heidenhain EnDat is an option on MPP/MPJ motors. It is compatible with the IPA servo drive, Aries servo drive and the Compax3 servo drive with the F12 feedback option.

The Stegmann Hyperface is available on the SMN and MPP/MPJ motors. These encoders are compatible with the Compax3 drive with F10 or F11 feedback option.

Heidenhain model numbers are EQI-1331 (multiturn 8D is p/n 811814-08), ECI 1317 (9D single-turn) and EQI 1329 (6D multi-turn) and EQI 1331 (7D multi-turn).

The 8D can be run in pure digital mode EnDat 2.2 but also has the analog commutation track for backwards compatibility as a 7D replacement (EnDat 2.1).

Parker Servo Drive compatibility with non-Parker motors with EnDat absolute encoders:

The IPA servo drive does not use the analog commutation track and can be run with a servo motor with EnDat 2.1 or 2.2, with or without the commutation track.

The Compax3 supports both 2.1 and 2.2 absolute encoders. With the C3 ServoManager's Motor Manager set for 2.2, it is pure digital and not using the commutation track.

The Aries uses the analog commutation track.

SICK (Stegmann) Hyperface SinCos part numbers are SRS50 (single-turn) and SRM50 (multi-turn).

SM and BE motors are available as custom with absolute encoders. Note for applications only needing higher resolution there is the L encoder option (5000 lines = 20,000 counts/rev post quadrature resolution) which is a standard incremental encoder. The above absolute encoders are physically too large to fit inside the back of the 23 frame servo motors; but we can provide the Heidenhain EQI1130 within a SM23 and BE23. We've done so already on numerous custom requests. The EQI1130 encoder is EnDat 2.1 and is 18 bit resolution (262,144 counts per revolution), multiturn with 4096 revs.

EnDat & Hyperface

*Change F to FH for high flex cables: F-1A2-xx is a static (non-flexing) cable. FH-1A2-xx is the high flex version of the cable cable.

BiSS-C

*APCS cables are in length of meters, standard lengths of 3, 5, 10 or 20. Example, APCS-EN03ES1 is the 3m cable high flex cable. The N designates high flex. Static cables (non-flexing) 3meter length is:  APCS-EF03ES1

BiSS-B

Our motors currently do not offer this option. The P series drives are compatible with BiSS-B absolute encoders.

Hyperface DSL

Standard option on the MPP/MPJ series motors.

** The 7D is no longer offered by Heidenhain. The 8D can be used in place. It can has the same resolution as the 7D and works with the IPA, Aries and Compax3 F12 without any changes.

*** The 6D is no longer offered by Heidenhain. The 7D can be used in place. With the Aries drives use the command ISIN -2 to lower the feedback resolution 2bits from 19bits to 17bits for replacements.

3/15jh added 8D.

11/13 jh corrected 6S/9S resolution. added note on BE23/SM23.

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