F31 Square Laser Photoelectric Switch (Diffuse-Reflective & Through-Beam)

Name: F31 Square Laser Photoelectric Switch (Diffuse-Reflective & Through-Beam)
Brand: DAIDISIKE
SKU: f31-square-laser-photoelectric-switch
Availability: InStock

Compact square-housing 650nm laser switch: diffuse-reflective 50-300mm or through-beam up to 50m, NPN/PNP, NO/NC.

F31 Square Laser Photoelectric Switch (Diffuse-Reflective & Through-Beam) - product detail

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Technical Specifications

Type	Laser photoelectric switch (square housing, diffuse-reflective / through-beam)
Light source	650nm red laser
Detection method	Diffuse-reflective (F31300); through-beam (F3150M)
Detection distance	Diffuse-reflective: 50-300mm; through-beam: 50m
Output type	NPN / PNP, NO (suffix 1) / NC (suffix 2)
Working voltage	10-30VDC
Housing shape	Square
Protection rating	IP65

Overview

The F31 is a laser-based photoelectric proximity switch built into a compact square housing. It uses a 650nm visible red laser diode instead of a standard infrared LED, letting the installer see the actual laser spot on the target for precise alignment when detecting small parts. It ships in two functional variants: F31300 (diffuse-reflective), a single housing that emits and receives its own laser and detects an object when the beam reflects back; and F3150M (through-beam / opposed), a matched transmitter + receiver pair mounted facing each other that detects an object when it breaks the beam between them.

The F31300 diffuse-reflective variant has a detection distance of 50-300mm, while the F3150M through-beam pair reaches up to 50m. Output is field-selectable between NPN and PNP, with normally-open (suffix 1) or normally-closed (suffix 2) switching action, and the sensor operates on a 10-30VDC supply with an IP65 protection rating. It suits machine builders, panel integrators, and OEMs building packaging machinery, conveyor systems, and small automation cells who need a compact, visible-beam laser sensor with configurable output for direct PLC wiring.

Key Facts — F31 at a glance

The F31 series is a 650nm visible red laser photoelectric switch available in diffuse-reflective (F31300, 50-300mm) and through-beam (F3150M, up to 50m) configurations.
F31 sensors operate on a 10-30VDC supply and are rated IP65.
Output is field-selectable between NPN and PNP, with normally-open (suffix 1) or normally-closed (suffix 2) switching action.
The F3150M through-beam variant is supplied as a matched transmitter-receiver pair, with the transmitter identified by a green indicator LED and the receiver by a yellow indicator LED.
Wiring follows a standard 3-wire scheme: brown for positive supply, blue for negative supply, and black for signal output.
The sensor housing includes an on-board VR potentiometer for on-site adjustment of the diffuse-reflective detection point.

Features & Benefits

Visible red laser spot for precise targeting

Unlike infrared photoelectric sensors, the 650nm red laser beam is visible to the naked eye, letting installers see exactly where the detection point falls and align the sensor on small or narrow targets without extra tools.

Two detection modes in one compact square housing family

Diffuse-reflective (F31300, 50-300mm, self-contained) and through-beam (F3150M, up to 50m, transmitter+receiver pair) share the same square housing design and output logic, simplifying spare-parts stocking and design familiarity across a machine.

Long-range through-beam detection up to 50m

The F3150M through-beam pair extends detection well beyond typical short-range diffuse sensors, suitable for monitoring wide gaps, long conveyor spans, or perimeter-style beam-break applications.

Flexible output configuration (NPN/PNP x NO/NC)

Each variant is available as NPN or PNP output, normally-open (suffix 1) or normally-closed (suffix 2), so the same sensor family can be wired directly into either sinking or sourcing PLC input cards without external relays.

Wide supply voltage range for standard industrial 24VDC systems

Operating at 10-30VDC covers common industrial control voltages (12V, 24V) with margin, giving flexibility when integrating into existing control cabinets.

IP65-rated housing for factory-floor environments

The IP65 protection rating provides dust-tight and water-jet-resistant sealing, suitable for typical factory production-line conditions where dust and occasional washdown or spray are present.

Simple 3-wire connection with clear color coding

The factory wiring diagram shows a standard 3-wire scheme (brown = V+, blue = V-, black = signal output), with documented NPN/PNP and NO/NC signal behavior, making field wiring straightforward for electricians unfamiliar with the specific model.

On-board potentiometer (VR) for sensitivity/distance adjustment

The dimension drawing shows a VR (variable resistor) adjustment point alongside the LED indicator on the sensor face, allowing the diffuse-reflective detection point to be fine-tuned on site.

Applications

Small-part presence detection on assembly or packaging lines — The 650nm visible laser spot with adjustable 50-300mm diffuse-reflective range makes it suitable for confirming the presence of small components without needing a reflector or receiver on the opposite side.

Long-span conveyor jam or object-passage detection — The F3150M through-beam pair's 50m range fits monitoring points spaced far apart, such as across a wide conveyor or along a long line, where a diffuse sensor's shorter range would not reach.

Carton/box counting or gap detection on packaging equipment — Selectable NO/NC output and NPN/PNP wiring let the sensor integrate directly into existing packaging-line PLC logic for triggering counters or gates.

Precise alignment tasks where beam visibility matters — Because the laser spot is visible, technicians can visually confirm the sensor is aimed at the intended detection point during commissioning - a practical advantage over infrared sensors on tight or narrow targets.

Retrofit sensor replacement in existing 24VDC control cabinets — The 10-30VDC supply range and standard 3-wire NPN/PNP output match the wiring conventions of common industrial control cabinets, easing retrofits.

Compact-space installation as an alternative to cylindrical sensors — The square housing form factor offers an alternative mounting profile to cylindrical laser sensors for equipment designers with bracket or panel constraints.

Position/gap sensing on light industrial machinery panels — The compact square body and dual NO/NC option suit OEM panel builders needing a small, direct-wire sensor rather than a larger housing.

Models & Ordering Information

F31300 Diffuse-Reflective (50-300mm)

F31300N1F31300P1F31300N2F31300P2

N1=NPN NO, P1=PNP NO, N2=NPN NC, P2=PNP NC. Diffuse-reflective type: a single unit emits and receives its own laser, no separate receiver needed.

F3150M Through-Beam (50m)

F3150MN1F3150MP1F3150MN2F3150MP2

N1=NPN NO, P1=PNP NO, N2=NPN NC, P2=PNP NC. Through-beam type: transmitter and receiver are sold and used as a matched pair.

How to Select

Choose F31300 (diffuse-reflective) for single-side installation with self-contained emit/receive and no receiver needed on the opposite side; detection distance is 50-300mm.
Choose F3150M (through-beam) for longer detection distances or when the target fully blocks the beam path (e.g. cartons, large objects, wide gaps); detection distance is up to 50m, and requires the transmitter and receiver to be installed as a pair (transmitter = green indicator, receiver = yellow indicator).
For NPN PLC input cards (common-positive, low-level output), choose the N variant (e.g. F31300N1, F3150MN1).
For PNP PLC input cards (common-negative, high-level output), choose the P variant (e.g. F31300P1, F3150MP1).
Choose suffix 1 (NO) if the signal should go from off to on when an object is detected.
Choose suffix 2 (NC) if the signal should go from on to off when an object is detected.
Confirm the supply voltage at the installation site falls within the 10-30VDC range.
The F31 has a square housing; if the equipment already has mounting holes for a cylindrical (M-series) sensor, confirm whether switching to the square F31 requires re-drilling or a different bracket.

📘 Need the full method? NPN vs PNP Sensor Outputs Explained

When NOT to specify the F31 — and what to use instead

The target is dark or matte near the far end of the F31300 diffuse range, or the equipment only has cylindrical M-series mounting holes

Why not: Diffuse detection distance (50-300mm) is reflectivity-dependent, and the F31's square body may not fit existing M12/M18 brackets without re-drilling, per the product's own selection guide.

Use instead: the DDSK/DK M12/M18 laser diffuse sensor for a cylindrical body, or a through-beam pair for reflectivity-independent detection

A diffuse detection point beyond 300mm is needed

Why not: The F31300 diffuse variant is rated 50-300mm; there is no longer-range diffuse option within this square-body family.

Use instead: the F3150M through-beam variant (rated to 50m) if two mounting points are workable

Only one mounting side is available

Why not: The F3150M through-beam variant is a matched transmitter-receiver pair that must be mounted facing each other; a single mounting point won't work with this variant.

Use instead: the F31300 diffuse variant, which needs only one mounting point and no receiver

Machine guarding or personnel-safety interlocking

Why not: Both F31 variants document only IP65 and 10-30VDC electrical ratings; neither carries a stated safety-function certification.

Use instead: a dedicated safety light curtain, never either F31 variant, for guarding

Specifications we do not publish yet

We only publish a figure once we are confident it is true. The items below are still being validated through further testing and real-world customer feedback, so for now we would rather leave them open than guess. If one of them matters to your design, ask us for the latest validated status.

Laser safety class (only 650nm wavelength is documented)
Minimum detectable object size
Response time / switching frequency
Hysteresis (repeat accuracy)
MTBF
Exact operating/storage temperature range
Cable/connector specification
Certification (CE/UL/RoHS etc.)

Frequently Asked Questions

What is the difference between the F31300 and F3150M variants?

F31300 is a diffuse-reflective sensor - a single unit both emits and receives the laser and detects an object when the beam reflects back, with a detection range of 50-300mm. F3150M is a through-beam (opposed) sensor sold as a transmitter-receiver pair, mounted facing each other; it detects an object when it breaks the beam between them, with a detection range up to 50m.

What does the N and P in the model number mean?

N indicates NPN output and P indicates PNP output. NPN is a common-positive-voltage, negative-signal-output configuration; PNP is a common-negative-voltage, positive-signal-output configuration, per the factory wiring diagram.

What does the 1 and 2 suffix mean?

Suffix 1 indicates normally-open (NO) output - the signal activates when an object is detected. Suffix 2 indicates normally-closed (NC) output - the signal is active by default and de-activates when an object is detected.

What light source does the F31 use, and why does that matter?

It uses a 650nm visible red laser diode rather than a standard infrared LED. Because the beam is visible to the naked eye, installers can see exactly where the detection spot falls, which helps when aligning the sensor on small or precisely positioned targets.

How is the F31 wired?

It uses a standard 3-wire connection: brown = positive supply (V+), blue = negative supply (V-), and black = signal output. The signal behavior (active-high or active-low, NO or NC) depends on the specific NPN/PNP and 1/2 model variant ordered.

What supply voltage does the F31 need?

10-30VDC.

What is the housing protection rating?

IP65, indicating dust-tight sealing with protection against water jets.

Is the detection distance adjustable on the diffuse-reflective model?

The sensor's dimension drawing shows an on-board VR (potentiometer) adjustment point next to the LED indicator, allowing the diffuse-reflective detection point to be fine-tuned on site within its 50-300mm range.

How do I tell the transmitter from the receiver on the F3150M pair?

The transmitter unit is marked with a green indicator light and the receiver unit with a yellow indicator light.

Can you provide certification documents for this sensor?

Certification documents are available on request.