Optical absolute encoder
HEIDENHAIN RCN 2001 / RCN 5001 angle encoders
Absolute angle encoders with integral bearing and hollow through-shaft for rotary tables and swivel heads.
Key specifications
| Speed (max) | 3,000 rpm |
|---|---|
| Bore (max) | 35 mm |
| Resolution (max) | 28 bit |
| Accuracy | system accuracy ±2" (RCN 2001) / ±4" (RCN 5001) |
| Interface | EnDat 2.2, Fanuc αi, Mitsubishi high speed |
Summarised in our own words from DR. JOHANNES HEIDENHAIN GmbH's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1
Notes on this data
26 bit / 28 bit; hollow shaft 20 / 35 mm; 3000 rpm with purely serial interface. Paired values assumed in series order. Page does not say whether these succeed the older RCN 2000/5000 names.
Specify Motion is not affiliated with DR. JOHANNES HEIDENHAIN GmbH. HEIDENHAIN and RCN 2001 / RCN 5001 angle encoders are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with a HEIDENHAIN part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These series from our supply network is the closest match on published figures.
Multi-turn absolute hollow-shaft capacitive encoder that holds position through power loss, so no re-homing.
| Published maximum | RCN 2001 / RCN 5001 angle encoders | VLM |
|---|---|---|
| Resolution | 28 bit | 32 bit meets or exceeds |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
What an optical absolute encoder is
An optical absolute encoder reads a unique code pattern on a disc or scale, so every position has its own digital value and position is known immediately at power-up. Single-turn encoders give position within one revolution; multi-turn encoders also count revolutions using gears or electronic counters. Position is sent over a serial interface such as SSI or BiSS, a manufacturer-specific protocol, or a fieldbus. Optical scanning gives high resolution, typically 17 bits per revolution or more in servo encoders, and good accuracy.
When engineers choose an optical absolute encoder
Choose an optical absolute encoder where knowing position at power-up matters, such as robots, machine tools, multi-axis machines and axes that cannot be homed safely. It removes homing routines and supports safety functions. The trade-offs are cost, interface compatibility and contamination sensitivity. Battery-backed multi-turn types need battery maintenance; gear or energy-harvesting types avoid that. In very dirty environments, magnetic or inductive absolute encoders may suit better.
How to specify the HEIDENHAIN RCN 2001 / RCN 5001 angle encoders
Send these with your enquiry and an engineer can confirm the right RCN 2001 / RCN 5001 angle encoders variant or an equivalent:
- Single-turn resolution (bits)
- Multi-turn range (revolutions)
- Interface: SSI, BiSS, proprietary serial or fieldbus
- Accuracy (arcsec)
- Shaft or hollow shaft size (mm)
- Speed (rpm)
- Environment and safety rating
Common mistakes to avoid
- Choosing an interface the drive does not support
- Forgetting battery maintenance on battery-backed multi-turn types
- Confusing resolution with accuracy
- Ignoring cable length limits for serial interfaces
HEIDENHAIN RCN 2001 / RCN 5001 angle encoders: frequently asked questions
What is the HEIDENHAIN RCN 2001 / RCN 5001 angle encoders?
Absolute angle encoders with integral bearing and hollow through-shaft for rotary tables and swivel heads. Published series figures include speed 3,000 rpm, bore 35 mm, resolution 28 bit. It is made by DR. JOHANNES HEIDENHAIN GmbH; Specify Motion can help source it or propose an equivalent.
Who makes the HEIDENHAIN RCN 2001 / RCN 5001 angle encoders?
The HEIDENHAIN RCN 2001 / RCN 5001 angle encoders is made by HEIDENHAIN (DR. JOHANNES HEIDENHAIN GmbH) and is listed here for engineers comparing options. Specify Motion is not affiliated with DR. JOHANNES HEIDENHAIN GmbH; brand names are used only to identify the product.
What is the speed of the HEIDENHAIN RCN 2001 / RCN 5001 angle encoders?
The published series maximum speed is 3,000 rpm. Individual models and sizes in the RCN 2001 / RCN 5001 angle encoders range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the HEIDENHAIN RCN 2001 / RCN 5001 angle encoders?
Yes. On published figures, Netzer Precision VLM is the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
What is the difference between single-turn and multi-turn absolute encoders?
A single-turn absolute encoder knows its angle within one revolution. A multi-turn absolute encoder also counts complete revolutions, so it knows total position over many turns even after power loss. Multi-turn encoders avoid homing on axes driven through screws or gears.
Which interface should an absolute encoder use?
Use the interface supported by the drive or controller. SSI is simple and widely supported, BiSS-C is an open bidirectional protocol, and several manufacturer-specific protocols are common on machine tools and servo drives. Fieldbus encoders suit PLC networks. Check cable lengths and update rates for the control loop.
Further reading: Absolute vs incremental encoders · How to select an encoder · Encoders and feedback
Other optical absolute encoder series
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