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Part of the Omron Photoelectric Sensors series — see the full model table, lifecycle status and replacement parts.

Omron E3FA-RP21 M18 retro-reflective photoelectric sensor — front view showing the M18 ABS plastic body with the polarized red 624 nm LED transmitter/receiver lens on the front face, the operation indicator (orange) and stability indicator (green) LEDs visible on the rear

Omron E3FA-RP21 — M18 Retro Reflective, 4 m, PNP

SKU: E3FA-RP21

USD 16.50

M18 cylindrical ABS plastic retro-reflective photoelectric sensor with polarized MSR (mirror-surface rejection), red 624 nm LED

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Product Overview

The Omron E3FA-RP21 is the polarized retro-reflective variant of Omron's E3FA cylindrical M18 photoelectric sensor family — an ABS plastic housing with a built-in polarized MSR (mirror-surface rejection) filter that distinguishes real targets from shiny reflections. It is manufactured by Omron Corporation. Hengyixin Automation ships this sensor from our Xiamen warehouse with a 30-day DOA return window and a datasheet PDF included in the box.

Response time 0.5 ms 100 mm minimum sensing distance Response time 0.5 ms 100 mm minimum sensing distance

The polarized MSR filter costs ~30 % of the sensing distance vs non-polarized retro-reflective (where 7 m is typical with E39-R1S on E3FA-RP-1 7m max), so the trade-off is range for shiny-target filtering.

Key Features

  • Response time 0.5 ms
  • 100 mm minimum sensing distance
  • M12 4-pin quick-disconnect connector
  • M18 cylindrical ABS plastic housing
  • SKU: E3FA-RP21
  • Series: E3FA M18 Cylindrical Photoelectric Sensor
  • Voltage: 2 V

Best-Fit Applications

  • Glass bottle counting on a bottling line — E3FA-RP21 with E39-R1S reflector at the fill-station trigger point; the MSR filter.
  • Aluminum can detection on a canning line — sensor detects cans passing the trigger point; polarized filter rejects the highly-reflective.
  • Shiny plastic toy detection on an automated assembly conveyor — the toy has molded shiny surfaces; standard retro-reflective would false-trigger.

Buying Checklist

  • Pick E3FA-RN21 for NPN output — pick for legacy NPN/sinking PLC inputs
  • Pick E3FA-RP21 for M18 plastic retro-reflective with MSR, PNP, M12 connector, 4 m with E39-R1S
  • Pick E3FB-RP21 for M18 nickel-brass housing — pick for machine-tool coolant or food-processing washdown environments

Technical Specifications

Model E3FA-RP21
Series E3FA M18 Cylindrical Photoelectric Sensor
Type M18 retro-reflective with MSR, ABS plastic body, PNP, M12 connector
Sensing Method Retro-reflective with polarized MSR filter
Sensing Distance 4 m with E39-R1S reflector (sold separately); 6 m with E39-R2 large reflector
Min. Sensing Distance 100 mm
Standard Sensing Object Opaque, 80 mm dia min
Light Source Red LED, 624 nm, polarized
Output Type PNP open-collector, Dark-ON / Light-ON selectable
Switching Capacity 100 mA at 30 VDC
Residual Voltage 2 V max at 100 mA load
Supply Voltage 10 to 30 VDC, ripple 10 % p-p max
Current Consumption 25 mA max
Operating Temperature -25 to +55 °C (no icing)
Storage Temperature -30 to +70 °C

Manufacturer documentation

Omron's own product page, where the manufacturer's current specification and lifecycle information are published. We are an independent distributor and cannot mirror those documents; the link goes to Omron's site.

FAQ for E3FA-RP21

What is MSR (mirror surface rejection) on the E3FA-RP21?
MSR (mirror surface rejection) is a polarization-filter technique that allows the sensor to detect only real beam interruptions, not reflections from shiny surfaces. The sensor emits red light polarized at 90° (vertical). When this light hits the corner-cube retroreflector (E39-R1S), the corner-cube rotates the polarization 180° back to vertical, so it passes through the receiver's vertical-polarization filter.
What reflector do I need for the E3FA-RP21?
The E3FA-RP21 works with the E39-R1S corner-cube retroreflector (40 × 60 mm) for 4 m range, or the larger E39-R2 (80 × 80 mm) for 6 m range. The E39-R1S is the standard pick; the E39-R2 is for installations with longer distances. For smaller-distance installations where space is tight, the E39-R3 (15 × 30 mm small) reduces range to ~1 m. Order the reflector separately — it's not included with the sensor.
Can the E3FA-RP21 detect a clear-glass bottle?
Yes — the E3FA-RP21 detects clear-glass bottles (and clear PET, clear water bottles) because the beam must physically pass through the glass to reach the reflector, and the bottle blocks enough of the beam to trigger the sensor. Clear PET reduces beam transmission by ~20 %; clear glass by ~10 %; both are reliably detected at the 4 m E39-R1S range.
What's the difference between E3FA-RP21 and E3FA-RP11 2M?
E3FA-RP21 (this SKU) uses an M12 4-pin connector — the cable is removable and replaceable; the sensor body has an M12 connector port. E3FA-RP11 2M uses a pre-wired 2 m PVC cable — the cable is integral to the sensor body and cannot be replaced without replacing the sensor. Both have identical electrical specs (4 m range with E39-R1S, PNP, MSR polarized, IP67/IP69K).

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