RM20 Linear Encoder
Absolute linear position feedback with 0.03 µm accuracy and an unlimited cascading range — the long-travel solution that keeps its precision to the last millimeter.
Long travel. Full precision. Zero loss.
The RM20 measures linear displacement through the same inductive principle as the RM10, driven by the AFEA1001 IC and a dedicated linear controller. Its signature feature is infinite cascading: scale segments join without accumulated error, so measurement range grows without sacrificing accuracy.
- 0.03 µm absolute linear accuracy
- Infinite cascade — extend range without precision loss
- Up to 1 m/s linear speed
- Immune to oil, coolant, dust and metal chips
- IP67, −40 ~ +85 °C, vibration and shock tested
- RS485 · BISS-C · SSI with shared 8-pin terminal
| Product model | RM20 |
| Core chip | AFEA1001 self-developed inductive sensing SoC |
| Sensing principle | Inductive (eddy-current coupling) |
| Output | Absolute — position retained on power loss, no homing required |
| Sensing accuracy | 0.03 µm |
| Calibration | One-key, tool-free — move the slider one sensing period under power and the zero point is captured automatically |
| Maximum linear speed | 1 m/s |
| Measuring range | Infinite cascading — single-stage accuracy is not degraded by cascading (exclusive) |
| Communication protocols | RS485 / BISS-C / SSI |
| Communication frequency | ≤ 16 kHz |
| Supply voltage | 2.5 V – 5.5 V |
| Working current | 15 mA typical |
| Operating temperature | −40 °C to +85 °C |
| Protection rating | IP67 (optional enhanced coating) |
| ESD protection | IEC 61000-4-2, ±12 kV |
| Vibration | 10–55 Hz, 1.5 mm amplitude; 55–2000 Hz, 98 m/s² · XYZ, 2 h each |
| Mechanical shock | 980 m/s², 11 ms, 3 times per direction |
| Insulation resistance | 50 MΩ |
| Low-power modes | Sleep < 25 µA · Deep Sleep < 2 µA |
Notes: Sensing accuracy (0.03 µm) refers to the measurement principle, verified static at 25 °C; the 17-bit output protocol quantizes the measured position to its own step, and higher bit-width output is available on request. ≤ 16 kHz is the serial communication update rate; maximum linear speed is a mechanical rating — the two parameters are independent.
Try the RM20 sensing principle
Drag the read head along the scale — watch absolute linear position update in real time.
Infinite cascading, explained
Traditional linear encoders lose accuracy as the scale gets longer, and very long scales become expensive and fragile. The RM20 solves this with a periodic mapping function that lets segments join seamlessly:
- Add segments to extend range — accuracy stays at 0.03 µm
- No mechanical joints, no calibration drift between segments
- Ideal for maglev tracks, long-stroke linear motors, gantry systems
- Single module pitch: 168 mm — segments join without accumulated error
Where the RM20 excels
Linear motors
Precise positioning for linear-motor stages in semiconductor, laser and additive manufacturing equipment.
Maglev systems
Unlimited cascading range for long maglev transport and handling lines without precision loss.
Precision platforms
Nanometer-class motion stages in metrology, inspection and photonics alignment.
Automation lines
Long conveyor and gantry feedback in oily, dusty production environments where optical scales fail.
Warehouse & logistics
Position feedback for high-speed sorters and shuttle systems running around the clock.
New energy systems
Linear actuators for solar tracking and wind applications in extreme outdoor temperature ranges.
RM20 linear encoder: questions buyers ask
Direct answers for engineers evaluating an absolute linear inductive encoder.
What is the RM20 encoder?
The RM20 is an absolute inductive linear encoder with 0.03 µm sensing accuracy at up to 1 m/s, built on the same AFEA1001 inductive sensing core as the RM10.
How accurate is the RM20?
Accuracy is 0.03 µm with true absolute output — position is known immediately at power-up, no reference run required.
How does infinite cascading work?
Read heads can be joined along the scale for unlimited travel; absolute accuracy stays unaffected as the measuring range is extended, unlike incremental tape systems.
Which communication protocols does it support?
RS485, BISS-C and SSI on a shared 8-pin terminal, matching the RM10 rotary encoder for mixed-axis machines with one supplier and one interface.
What are typical RM20 applications?
Linear motors, precision stages, machine tools, maglev tracks and long-travel automation where 0.03 µm accuracy and IP67 robustness matter.
Is the RM20 rated for harsh environments?
Yes — operating from −40 °C to +85 °C, IP67 protection, ±12 kV ESD and 100% factory tested, with low power consumption of ≤15 mA.
Test 0.03 µm on your own stage
Request an RM20 sample with evaluation board and protocol documentation — our team supports your integration end to end.