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.
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.
The Heidenhain EnDat is an option on MPP/MPJ motors. It is compatible with the Aries servo drive and the Compax3 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 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).
SICK (Stegmann) 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 (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.
| Encoder | Turns | Resolution | IPA | Cable | Aries | Cable | Compax3 | Cable |
| Heidenhain EnDat 8D | Multi | 19bits (524,288 ppu), 4096 turns | IPAxx-HC | F-1A2-xx | AR-xxAE, AR-xxPE, AR-xxCE | F-1A2-xx | F12 option | F-2A2-xx |
| Heidenhain EnDat 7D* | Multi | 19bits (524,288 ppu), 4096 turns | IPAxx-HC | F-1A2-xx | AR-xxAE, AR-xxPE, AR-xxCE | F-1A2-xx | F12 option | F-2A2-xx |
| Heidenhain EnDat 9D | Single | 17bits (131,072 ppu) | IPAxx-HC | F-1A1-xx | AR-xxAE, AR-xxPE, AR-xxCE | F-1A1-xx | F12 option | F-2A2-xx |
| Heidenhain EnDat 6D** | Multi | 17bits (131,072 ppu), 4096 turns | Not compatible | N/A | Not compatible | N/A | F11 option | F-2B1-xx |
| Stegmann Hyperface 6S | Multi | 16bit (65,536 ppu), 4096 turns | Not compatible | N/A | Not compatible | N/A | F11 option | F-2B1-xx |
| Stegmann Hyperface 9S | Single | 16bit (65,536 ppu) | Not compatible | N/A | Not compatible | N/A | F11 option | F-2B1-xx |
| Stegmann Hyperface 5D (SMN motors) | Multi | 16bit (65,536 ppu), 4096 turns | Not compatible | N/A | Not compatible | N/A | F11 option | F-2B1-xx |
The IPA now also has support for Biss-B / BiSS-C and Hyperface DSL. Available now as custom motors (contact your local Parker ATC for price quote)
See this FAQ for details on Biss support IPA MISC - ABSOLUTE ENCODER COMPATIBILITY (BISS-B AND BISS-C)
* The 7D is no longer offered by Heidenhain. The 8D can be used in place. It was the same resolution as the 7D and works with the Aries and Compax3 without any changes at the drive necessary.
** 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.