Absolute Magnetic Linear Encoder — OTV-AL200 Series
The OTV-AL200 Series is a true dual-track absolute magnetic linear encoder system — a complete solution that includes a readhead paired with a high-quality linear magnetic encoder strip. No homing. No battery. No incremental counter to lose.
- Up to 0.1 μm absolute resolution
- 16,384 mm (16.38 m) unique absolute code length
- Protocols: BiSS-C, SSI, RS-485, Panasonic, Tamagawa
- IP67 epoxy-potted readhead — valid position within 350 ms
What Is an Absolute Magnetic Linear Encoder?
In linear motion control, magnetic encoders have overtaken optical systems as the preferred choice in harsh industrial environments — non-contact, wear-free operation with no glass disc to break and no optical path to keep clean.
The OTV-AL200 Series is a true dual-track absolute magnetic linear encoder system. Unlike incremental systems that lose position at power-off, the AL200 delivers a valid, unique absolute position within 350 ms of power-up. No homing routine. No battery backup. No incremental counter to lose.
Sensor Readhead
An IP67 epoxy-potted readhead integrating a sensor IC (compatible with iC-MU and iC-MU200 series) that reads two parallel magnetic tracks simultaneously.
Magnetic Encoder Tape
A dual-track magnetic strip with an incremental (master) track and an absolute (nonius) track, mounted directly to the machine surface.
Non-Contact Sensing
Zero mechanical wear and extremely low signal latency (< 62.5 μs), making the AL200 ideal for high-bandwidth servo control loops.
How It Works: Dual-Track Magnetic Encoding
The AL200 readhead reads two parallel magnetic tracks on the encoder strip simultaneously.
Incremental Track (Master)
A precise alternating N-S pole pattern with a standard 2 mm pole pitch. This track provides high-resolution relative position data through the sensor’s onboard interpolator.
Absolute Track (Nonius)
A uniquely coded binary pattern that repeats only once over the entire 16,384 mm measurement range. The readhead compares the phase difference between the two tracks — using the Nonius (Vernier) principle — to compute a unique absolute position within one code cycle.
Key advantage over incremental encoders: No reference mark search on startup. If a machine axis loses power mid-operation, it recovers its exact position immediately — critical for safe restart in automated production lines, semiconductor handling, and multi-axis gantry systems.
Why Choose the OTV-AL200?
Engineered for precision, durability, and seamless industrial integration.
True Absolute on Startup
350 ms to valid position. No homing, no battery, no lost reference marks — critical for safe restart and multi-axis systems.
Contamination-Proof
IP67 epoxy-potted readhead with magnetic sensing — no optical path to obstruct. Waterproof, oil-proof, and dust-resistant.
Broad Protocol Support
BiSS-C, SSI, RS-485, Panasonic, and Tamagawa — compatible with mainstream drives and controllers.
Sub-Micron Resolution
0.1 μm absolute resolution supports the most demanding positioning applications.
Long Measurement Range
16.38 m unique absolute code length; tapes can be joined for longer axes.
Stainless Steel Housing
Rugged mechanical design with excellent EMC compatibility for industrial environments.
OTV-AL200 Encoder System
Performance Specifications
The OTV-AL200 is engineered for stability and broad controller compatibility.
| Parameter | Specification | Notes |
|---|---|---|
| Absolute Resolution | Up to 0.1 μm | Sub-micron precision control |
| Max Travel Speed | 5 m/s | Suitable for high-speed linear motors |
| Unique Code Length | 16,384 mm | Unique absolute position over 16.38 m |
| System Accuracy | ±20 μm/m | Tape accuracy; can be improved with calibration |
| Communication Protocols | BiSS-C, SSI, RS-485, Panasonic, Tamagawa | Broad drive and controller compatibility |
| Supply Voltage | 4.75 – 5.5 VDC | Reverse polarity protected |
| Protection Class | IP67 (epoxy potted) | Waterproof, oil-proof, dust-resistant |
| Position Update Latency | < 62.5 μs | Suitable for high-bandwidth servo loops |
| Startup Time | ~350 ms | Absolute position available; no homing |
Environmental & Mechanical
| Parameter | Specification |
|---|---|
| Readhead Operating Temp | –10 °C to +55 °C |
| Readhead Storage Temp | –20 °C to +85 °C |
| Magnetic Tape Temp Range | –20 °C to +70 °C |
| Vibration Resistance | 300 m/s² (~30 G), 55–2000 Hz (IEC 60068-2-6) |
| Shock Resistance | 300 m/s² (~30 G), 11 ms |
| EMC Immunity | EN IEC 61000-6-2:2019 |
| EMC Emission | EN IEC 61000-6-4:2019 |
| Max External Magnetic Field | < 1 mT (operating); > 25 mT causes irreversible tape damage |
| Housing Material | Stainless steel — rugged, excellent EMC compatibility |
Typical Applications
The AL200 serves a broad range of precision linear motion applications across demanding industries.
Semiconductor Equipment
Wafer handling stages, inspection systems, lithography positioning.
Lithium Battery Manufacturing
Electrode winding, slitting, stacking, calendaring.
Linear Motors & Direct Drive
Iron-core and ironless linear stages, voice coil actuators.
CNC & Precision Machining
Linear axes on grinding machines, milling centers, EDM.
Medical & Laboratory Automation
Precision positioning stages, scanning systems, liquid handling.
3C & Electronics Assembly
Pick-and-place, dispensing, automated inspection.
Installation & Alignment
Magnetic encoder accuracy depends directly on maintaining the correct air gap and alignment tolerances between the readhead and the encoder strip.
Key Installation Tolerances
| Parameter | Tolerance |
|---|---|
| Recommended Air Gap | 0.3 ± 0.1 mm |
| Lateral Offset | Readhead centered over tape; excessive offset reduces field strength and degrades accuracy |
LED-Assisted Alignment
The OTV-AL200 features a built-in status LED for real-time alignment verification:
| LED State | Meaning | Action |
|---|---|---|
| Solid Green | Signal optimal — installation correct | None |
| Red Flashing | Marginal signal — gap near limit | Re-check air gap and alignment |
| Solid Red | No signal — gap too large, tape demagnetized, or readhead misaligned | Verify tape presence and gap; inspect for external magnetic field exposure |
Installation tip: Use a 0.3 mm plastic feeler gauge between the readhead and tape during mounting. After securing the readhead, move it along the full travel length and verify the LED remains solid green at every position before commissioning the axis.
Frequently Asked Questions
What is the difference between absolute and incremental magnetic linear encoders?
An absolute encoder outputs a unique position value immediately after power-up — no homing or reference mark search required. An incremental encoder counts pulses from a known reference and loses position when power is removed. The OTV-AL200 is a true absolute system: valid position data is available within 350 ms of power-on.
What air gap is required between the readhead and magnetic tape?
The recommended air gap is 0.3 ± 0.1 mm. Use the supplied 0.3 mm plastic feeler gauge during installation. The readhead LED provides real-time gap feedback — solid green indicates correct alignment across the full travel range.
Which communication protocols are supported?
BiSS-C, SSI, RS-485, Panasonic, and Tamagawa protocols are all supported. Select your protocol at time of order — the readhead hardware is common across all options.
Can the magnetic tape be cut to length on site?
Yes. The MSA series magnetic tape is supplied cut to your specified length. For lengths exceeding the 16,384 mm unique code cycle, multiple tape segments can be joined. Contact OTV for joining instructions and longer-axis reference designs.
What is the maximum measurement length?
A single tape segment provides a unique absolute code over 16,384 mm (16.38 m). For longer axes, multiple tapes can be joined. The readhead seamlessly transitions between segments.
Can the OTV-AL200 operate in harsh environments?
Yes. The readhead is IP67-rated and epoxy-potted for protection against water, oil, and dust. The magnetic sensing principle has no optical components to foul. The stainless steel housing provides excellent EMC shielding. Operating temperature range is -10 °C to +55 °C (readhead) and -20 °C to +70 °C (magnetic tape).
Is the OTV-AL200 compatible with standard servo drives?
Yes. With BiSS-C, SSI, and RS-485 protocol support, the AL200 interfaces directly with mainstream industrial servo drives and motion controllers from vendors including Elmo, Copley, Beckhoff, Siemens, and Mitsubishi.
Need an Absolute Linear Encoder for Your Application?
OTV Sensing provides complete absolute magnetic linear encoder systems — readhead + magnetic tape — with full technical support from installation to commissioning. Tell us your stroke length, accuracy requirements, and controller protocol.
Related Products & Resources
Explore OTV’s full range of precision encoder solutions for industrial automation, robotics, and motion control.
OTV Precision Sensing — Absolute Magnetic Linear Encoder Series. Specifications subject to change without notice. Document: OTV-AL200-TS-EN-2026.