Question 1

How do I choose between POSIMAG magnetic incremental encoder and traditional optical encoder?

Accepted Answer

Decision rule: environment + mechanical impact + resolution need + cost.

Choose POSIMAG (magnetic incremental) when:
• Dirty, oily, icy, chip-laden environment — magnetic technology is immune. Optical disks foul; readings break.
• High mechanical impact and vibration — magnetic ring mount is flexible, impact-resistant. Optical disks break.
• Air-gap tolerance is loose — POSIMAG accepts ±1 mm gap. Optical requires tight (±0.1 mm) tolerance.
• Mobile machinery, outdoor, heavy industry — POSIMAG life is 3-5× that of optical in these environments.
• Resolution 184,320-327,680 pulses/rev is enough? POSIMAG covers this. Higher resolutions (1 M+ ppr) require optical.
• Budget — POSIMAG typically 20-30% more economical.
• Typical use: Motor RPM measurement, conveyor speed, crane winch position, mobile-machinery wheel speed, outdoor equipment.

Choose optical encoder when:
• Ultra-high resolution (1 M+ ppr) is required.
• Clean enclosed environment — laboratory, precision CNC, small robotic joints.
• Compact size critical — some optical micro-encoders are <10 mm diameter; POSIMAG is typically >30 mm.
• Existing system optical-compatible — retrofit may be difficult if the controller only expects optical.

Rule of thumb: Industrial environment (dirt, oil, vibration) + standard resolution (50-100k pulses) → POSIMAG. Clean lab + ultra-high resolution → Optical. Türkiye industrial trend over the last decade: POSIMAG has displaced optical in industrial applications. Optical now remains only in niche ultra-precision areas.

Question 2

How is the POSIMAG rot system installed? What's the mechanical relationship between the PMIS4 reader and the PMIR ring?

Accepted Answer

POSIMAG rot is a two-component system — installation follows this logic:

1) PMIR (Magnetic Ring) — Moving Part:
The ring mounts on the rotating shaft. The shaft is a motor mill, conveyor pulley, or crane winch. Inner diameter (e.g., 20H7) must match the shaft outer diameter — interference fit or screw-mount.

• Inner diameter selection: Choose the PMIR ring matching the shaft outer diameter (20H7 standard, custom diameters on request).
• Mounting: Interference fit or radial-screw mounting at 2-3 points. For high-RPM (>3000 RPM), screw-mounting is recommended.
• Balance: The ring must be centred on the shaft axis — eccentricity <0.05 mm. Otherwise, measurement drifts.

2) PMIS4 (Reader Head) — Fixed Part:
The sensor head mounts on the fixed machine housing, placed 0.1-1 mm from the magnetic ring.

• Sensor-ring gap: 0.1-1 mm (±1 mm tolerance). Hold this gap mechanically constant via a mounting bracket.
• Alignment: PMIS4 must be parallel to the ring axis — angular deviation <3°.
• Lateral offset: Align with the centre of the ring's magnetic band — radial offset ±1 mm tolerance.

3) System Behaviour:
1. As the shaft rotates, the PMIR ring rotates with it.
2. The ring's N-S poles pass under PMIS4.
3. PMIS4 counts each passing pole and outputs A/B incremental pulses.
4. A PLC or counter card counts the pulses → angular position, RPM, direction.
5. The Z signal (one pulse per full revolution) zeros the PLC counter — reference point.

4) Common Mistakes (to avoid):
• Gap too narrow (<0.1 mm) → mechanical contact, ring wears.
• Ring axial deviation (eccentricity) → measurement oscillates each rotation.
• Ferromagnetic parts nearby (under a large steel bracket) → magnetic field distorted.
• Z signal at a specific point on the ring — misconfiguring the PLC's reset direction during installation.

Question 3

How do I choose between the 4 PMIR ring variants (PMIR4, PMIR5, PMIR7, PMIR7N)?

Accepted Answer

PMIR rings differ by inner diameter + outer diameter + pole count + resolution. Choice depends on your machine's existing shaft diameter + required resolution + mounting space.

PMIR4 — Standard:
• Pole count: 50/64/90 (other counts on request)
• Resolution: up to 184,320 pulses/rev (90 poles × ×4 count × high scaling)
• Inner diameter: 20H7 standard (other diameters on request)
• Size: Standard outer diameter
• Use: Standard industrial RPM measurement, conveyor pulleys, mid-to-high RPM.

PMIR5 — High Resolution:
• Resolution: up to 327,680 pulses/rev — highest in class
• Size: Larger outer diameter (for higher pole count)
• Aluminum housing with magnetic ring
• Use: Precision position and speed monitoring — servo backup, precision CNC axis, calibration test rigs.
• Limit: Large diameter, requires ample mounting space.

PMIR7 — Standard Alternative:
• Resolution: up to 184,320 pulses/rev (same as PMIR4)
• Differs from PMIR4: Different outer diameter, stainless/aluminum housing combination
• Use: When PMIR4 doesn't fit existing mounting, or when stainless housing is preferred.

PMIR7N — Non-Standard Diameter:
• 'N' suffix: Non-standard / Custom size
• Alternative inner/outer diameter variant of PMIR7
• For custom shaft diameters outside the 20H7 standard.
• Use: Custom machine designs where the existing shaft size doesn't match standard rings.

Decision steps:
1. Measure shaft diameter → matches standard ring (20H7)?
• Yes → PMIR4 or PMIR7 (by mounting space)
• No → PMIR7N or custom order
2. Resolution requirement:
• Standard 184,320 ppr sufficient → PMIR4/PMIR7
• High 327,680 ppr required → PMIR5
3. Mounting space:
• Compact → PMIR4
• Large area available → PMIR5 (high resolution + large diameter)
• Custom size → PMIR7N

Important: Whichever PMIR is chosen, the PMIS4 reader head is compatible with all PMIR rings (2 mm magnetic period is fixed). Switching the ring in a single system is possible — only calibration is updated.

Question 4

Resolution math: how do magnetic period + pole count + scaling factor work together?

Accepted Answer

POSIMAG rot resolution is the product of 3 parameters: pole count × ×4 quadrature × scaling factor (interpolation).

1) Magnetic Period:
• 2 mm standard (code 20) — only option in POSIMAG rot.
• Means a full magnetic cycle (N-S pair) every 2 mm on the ring.

2) Pole Count (PMIR4 example):
• PMIR4: 50 / 64 / 90 pole options.
• 90-pole ring → 90 magnetic cycles per full revolution.

3) ×4 Quadrature Decoding:
• Incremental A/B signals counted at 4 times — each edge (A rising/falling + B rising/falling) is a pulse.
• 90 poles × ×4 = 360 raw pulses per full revolution.

4) Scaling Factor (Interpolation):
• Electronics inside PMIS4 multiplies raw pulses by a factor of 1-65535 (interpolation).
• Standard factors are defined in the datasheet scaling table (50, 100, 200, 500, etc.).
• Example: 90 poles × ×4 × scaling 100 = 36,000 pulses/rev.
• Higher scaling → higher resolution. But pulse frequency must not exceed PMIS4's max capability (50 kHz standard).

5) Resolution × Speed Trade-off:
Pulse frequency = (RPM/60) × poles × ×4 × scaling

Example 1: Motor 1000 RPM. 90 poles × ×4 × 100 = 36,000 pulses/rev.
Pulse frequency = (1000/60) × 36,000 = 600 kHz.
This EXCEEDS PMIS4's 50 kHz standard limit — requires the 480 kHz high-frequency option.

Example 2: Motor 100 RPM. 90 poles × ×4 × 100 = 36,000 pulses/rev.
Pulse frequency = (100/60) × 36,000 = 60 kHz.
Slightly above 50 kHz — reduce scaling to 50: (100/60) × 18,000 = 30 kHz ✓

Maximum resolutions:
• PMIR4 (90 poles × ×4 × max scaling): 184,320 pulses/rev
• PMIR5 (higher pole count × max scaling): 327,680 pulses/rev
• PMIR7 (same as PMIR4): 184,320 pulses/rev

Practical recommendation: First calculate the required resolution, then check the pulse frequency against the maximum RPM. If 50 kHz is exceeded, reduce scaling or order the high-frequency (480 kHz) option.

Question 5

What is the Z signal (reference mark) used for? When is it mandatory?

Accepted Answer

POSIMAG rot is an incremental system — the A/B channels only output a pulse per pole. No absolute position information. The PLC doesn't know where it is after power-off. The Z signal (reference mark) solves this.

What is the Z Signal?
An extra magnetic pattern at a specific point on the magnetic ring. When the ring makes a full rotation, the sensor detects this point once and produces a special 'reference' signal (Z channel).

PLC Usage:
1. Power-on: The PLC doesn't know position. "Unknown" state.
2. Homing sequence: PLC slowly rotates the shaft in one direction.
3. Z signal detected: PLC zeros its counter.
4. Absolute position now known: Counter represents the angle within a 360° revolution.
5. Running: A/B pulses counted as shaft rotates, position updates.
6. New revolution: When Z is passed again, the counter is EXPECTED to return to 0 (verification). Deviation = error.

Problems without Z signal:
• Position unknown after power-off.
• Sensor failure cannot be detected (no verification).
• No full-revolution reference — if direction is lost in half a rotation, PLC error can't be corrected.

Z Signal Order Code:
Z mark is optional on PMIR rings:
• O = without — ring without Z (economical, for simple RPM measurement).
• M = with — ring with Z (for absolute position).

Counterpart "signal Z" token on PMIS4:
• Z0: A/B signal only, NO Z — PMIR ring must also have Z = O
• Z1: A/B + Z signal — PMIR ring must have Z = M
• Z2: A/B + Z + end-position signal — multi-segment applications
• Z3: A/B + Z + status signal (for single-ended output only)

Decision:
• RPM measurement only (direction + speed), position not critical → Z = O / Z0 sufficient (economical).
• Absolute position required (servo control, pallet conveyor, valve position) → Z = M / Z1 mandatory.
• Full-revolution verification + fault detection (critical safety) → Z = M / Z3 (with status signal).

The cost impact of the Z signal is minimal (~5% extra). When in doubt, ordering Z = M is safer.

Question 6

Inner diameter selection: 20H7 standard, custom diameters — how do I integrate it into the shaft?

Accepted Answer

The inner diameter of a PMIR ring must match the rotating shaft's outer diameter exactly. This is a critical mounting decision.

Standard Inner Diameter:
• 20H7 — industry-standard tolerance (per ISO 286, H7 = nominal +0/+21µm).
• Provides interference fit with a 20 mm shaft outer diameter.
• The ring seats on the shaft without screws and doesn't slide at normal RPM.

Custom Inner Diameters (on request):
ASM produces custom-diameter rings on demand. Common custom sizes:
• 10, 12, 15 mm — small motor shaft
• 25, 30 mm — medium shaft
• 40, 50 mm — large shaft, crane winch
• Larger diameters (>100 mm) — large industrial equipment, heavy machinery

Inner Diameter Selection Steps:
1. Measure the shaft outer diameter with a micrometer — not a rough measurement, accurate to ±0.01 mm.
2. Tolerance check: Shaft h6 or h7 → compatible with standard 20H7. Looser tolerance (h11) weakens the interference fit.
3. Inner diameter ring code: Last token in the ASM order code. "20" = 20H7. Other diameters: "15", "25", "30" etc.
4. Interference fit force: Ring is installed by hand onto a cold shaft; heating the shaft eases insertion.

Mounting Methods:
A) Interference Fit:
• Most common with standard 20H7.
• Ring is pressed onto the shaft; friction holds it.
• Sufficient for low RPM (<3000).
• Limit: Can slip at high RPM; may loosen under vibration.

B) Radial Screw Mount:
• 2-3 radial M3/M4 screw holes in the ring body.
• Ring sits on the shaft, then screws are lightly tightened (5-10 Nm).
• Recommended for high RPM (3000-10000).
• Advantage: Guaranteed retention, vibration-resistant.

C) Loctite + Interference Fit:
• Ring on standard 20H7, then Loctite (242 or 270) applied to the shaft surface.
• For high-RPM + long-life permanent installation.
• If disassembly is needed, heating breaks Loctite.

Eccentricity Tolerance:
Ring must be centred on the shaft axis. Eccentricity must be < 0.05 mm — otherwise the magnetic field passes at varying distances on each rotation, and the measurement oscillates. Interference fit usually ensures this.

Typical issue: If the shaft has a notch or protrusion, the ring won't centre properly. Ensure the shaft surface is PERFECTLY CYLINDRICAL at the measurement point — smooth, no grooves, no nicks.

Question 7

PMIS4 output signal (TTL, RS422, HTL) — how do I ensure PLC compatibility?

Accepted Answer

PMIS4 is offered in three different electrical output formats. Choice depends on the format supported by your PLC encoder card input.

TTL (5 VDC) — "TTL":
• 5 V digital signal, square wave.
• Single-ended — 1 wire per channel.
• Ideal for short distance (<10 m cable).
• Open-circuit, noise-sensitive over long distances.
• Use: PLC TTL encoder card, FPGA digital counting, motor control drivers nearby.
• Standard cards like Siemens SM338, Allen-Bradley 1756-IT6I accept TTL or RS422 — check datasheet.

RS422 (5 VDC Differential) — same "TTL" code:
• 5 V differential — 2 wires per channel (A + Ā, B + B̄, Z + Z̄).
• Noise-immune — up to 100 m noise-free transmission.
• Industry standard — most modern PLC encoder cards support RS422.
• Use: Standard industrial installation, 10-100 m cable length, noisy environment.
• Note: ASM's datasheet uses "TTL" to cover both single-ended TTL and RS422 (both 5 VDC excitation). Output configuration is selected at order time.

TTL24V (24 VDC Excitation, TTL/10 mA Output) — "TTL24V":
• 24 VDC excitation, TTL/10 mA output.
• Higher voltage swing → noise resistance + longer distance.
• For industrial automation (especially 24 VDC PLC systems).
• Use: Siemens S7 24 VDC encoder inputs, automation cards.

HTL (24 VDC Push-Pull) — "HTL":
• 24 VDC, push-pull output (10-30 V swing).
• Most robust, highest noise immunity.
• Mobile machinery and heavy industry standard.
• Use: Tractors, excavators, cranes, automotive ECU systems (Bosch, Sauer-Danfoss controllers).

Decision table:
• PLC encoder card accepts 5 V TTL, cable <10 m → TTL
• Standard factory industrial installation → RS422 (most common)
• 24 VDC PLC system (automation) → TTL24V
• Mobile machinery, heavy industry → HTL
• Long distance (>50 m) + noisy environment → HTL or RS422

Important: PMIS4 is factory-configured for a specific output format at shipment — no field update. At order time, verify your PLC card format. Wrong format selection means the PLC won't recognise the sensor.

Question 8

What are the POSIMAG rot warranty, calibration, and IMB Electric regional support conditions?

Accepted Answer

Warranty: ASM Sensor offers a 2-year manufacturer warranty on all POSIMAG rot models. Out-of-warranty cases:
• Mechanical contact between ring and sensor (unacceptably close gap, ring worn)
• Excessive ring eccentricity (>0.1 mm)
• Use outside datasheet limits (temperature, IP, magnetic interference)
• Unauthorised opening or repair
• Wrong PMIS4 + PMIR combination (incompatible magnetic period)

Calibration: POSIMAG rot operates contactlessly — no mechanical wear. Calibration intervals are long. Typically 5-10 years. For field verification:
• Mount the PMIS4 + PMIR system on a fixed reference-angle setup.
• Perform one full revolution, verify PLC count.
• Deviation must remain within ±0.1° (sensor + ring linearity limit).
• IMB Electric provides accredited calibration services in Türkiye (TÜRKAK scope).

Ring replacement: PMIR rings are contactless — no wear. The only failure modes are mechanical impact (ring breakage), excessive eccentricity (mounting error), or excessive temperature (>85°C, elastomer/magnetic degradation).

Sensor replacement: PMIS4 electronics are long-life. Failure mode is typically external impact (housing damage) or electrical fault (wrong voltage input, short).

System Replacement: When replacing either the ring or the sensor, ensure both use the same magnetic period (2 mm). Mismatched periods won't allow the system to operate.

IMB Electric Regional Support:
IMB Electric is listed for Türkiye on ASM Sensor's official global distribution network, with authorisation extending to Türkiye + the Middle East + North Africa + Western Asia.

Regional services:
• Stock delivery (İstanbul İkitelli OSB)
• Fast quotation (24-48 hours)
• Accredited calibration and repair (TÜRKAK scope)
• Application-based engineering support — sensor + ring selection, mounting help, PLC integration, custom inner-diameter orders
• Local management of warranty processes
• Turkish + English + Arabic (for the Middle East) technical documentation
• Field training (on request)

Contact: info@imbelectric.com · +90 212 544 59 59 · imbelectric.com

About the POSIMAG® rot — Magnetic Incremental Encoders series

01How do I choose between POSIMAG magnetic incremental encoder and traditional optical encoder?

02How is the POSIMAG rot system installed? What's the mechanical relationship between the PMIS4 reader and the PMIR ring?

03How do I choose between the 4 PMIR ring variants (PMIR4, PMIR5, PMIR7, PMIR7N)?

04Resolution math: how do magnetic period + pole count + scaling factor work together?

05What is the Z signal (reference mark) used for? When is it mandatory?

06Inner diameter selection: 20H7 standard, custom diameters — how do I integrate it into the shaft?

07PMIS4 output signal (TTL, RS422, HTL) — how do I ensure PLC compatibility?

08What are the POSIMAG rot warranty, calibration, and IMB Electric regional support conditions?