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 + Xianji 5361 linear controller |
| Sensing principle | Inductive (eddy-current coupling) |
| Resolution | 17-bit |
| Absolute accuracy | 0.03 µm |
| Maximum linear speed | 1 m/s |
| Measuring range | Infinite cascading — accuracy unaffected by range extension |
| Communication protocols | RS485 / BISS-C / SSI |
| Communication frequency | ≤ 16 kHz |
| Supply voltage | 2.5 V – 5.5 V |
| Working current | ≤ 15 mA |
| Operating temperature | −40 °C to +85 °C |
| Protection rating | IP67 (optional enhanced coating) |
| ESD protection | IEC 61000-4-2, ±12 kV |
| Vibration | 10 Hz – 2000 Hz, XYZ axes, 2 h each |
| Mechanical shock | 980 m/s², 11 ms, 3 times per direction |
| Low-power modes | Sleep < 25 µA · Deep Sleep < 2 µA |
Try the RM20 sensing principle
Drag the read head along the scale — watch absolute linear position and 17-bit counts 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
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 a 17-bit absolute linear inductive encoder with 0.03 µm absolute accuracy at up to 1 m/s, built on the same AFEA1001 inductive sensing core as the RM10.
How accurate is the RM20?
Absolute accuracy is 0.03 µm with 17-bit resolution, so the measurement is absolute and 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.