FOTEK Photoelectric Switch Photo Sensor MT-6MX MT6MX

Fotek MT-6MX | Mini Through-Beam Photoelectric Sensor — 6m Range, NPN & PNP Dual Output NO, 10–30VDC, IP67, Short-Circuit & Polarity Protection

Overview

The Fotek MT-6MX is a miniature through-beam photoelectric sensor built around the compact MT series housing — 13.5mm wide, 25mm tall, 30mm long — while delivering 6 metres of sensing range in the through-beam opposed configuration.

That combination of small body and long sensing distance is the core of the MT-6MX's value in industrial applications where physical installation space is constrained but the detection zone itself is wide.

Through-beam sensing places the emitter and receiver in separate housings on opposite sides of the detection zone. When the light beam between them is interrupted by a target, the receiver detects the loss of signal and the output switches.

This is the most reliable photoelectric detection method for opaque objects: the sensor does not rely on the target's surface reflectivity, size, or colour — it simply sees whether the beam has been blocked.

At 6m, the MT-6MX can span machine widths, conveyor gaps, entry points, and loading zones that most reflective or retroreflective sensors cannot cover from a single mounting position.

The simultaneous NPN and PNP dual output is a practical installation feature. Both outputs are available on the same receiver unit, so the sensor wires to either NPN (sinking) or PNP (sourcing) PLC input cards without swapping sensors or adding signal converters.

NPN connects to PLC cards where the input terminal is pulled low when the sensor activates; PNP connects to cards where the terminal is pulled high. Having both on one device means the same sensor supports both European and Asian machine PLC standards from a single stock.

The IP67-rated compact housing with short-circuit and polarity reversal protection makes the MT-6MX a practical choice for machine tool environments, conveyor systems, packaging machinery, and material handling lines where sensors routinely face coolant, vibration, and occasional wiring errors during maintenance.

Key Specifications

Through-Beam Sensing — The Most Reliable Photoelectric Mode

In diffuse and retroreflective photoelectric sensing, reliable detection depends partly on the target — its surface reflectivity, colour, and presentation angle all affect how much light returns to the receiver.

A highly reflective target on a retroreflective sensor may fool the detector; a matte-black surface on a diffuse sensor may produce insufficient return signal.

Through-beam sensing eliminates these variables entirely: the sensor measures the presence or absence of the beam, and the target's only required property is that it blocks the beam sufficiently to reduce the receiver's signal below threshold.

At 6m range, the MT-6MX spans detection zones appropriate for aisle monitoring, machine entry detection, conveyor width sensing, and pallet/vehicle detection in storage areas. The beam path runs from the separate emitter to the receiver — both require mounting and wiring, but the resulting detection is robust against target surface conditions, ambient reflections, and vibrating background surfaces that challenge reflective sensor types.

Compact MT Series Housing — Small Footprint, Big Sensing Range

At 13.5 × 25 × 30mm, the MT series housing is one of the smallest rectangular enclosures in the Fotek photoelectric line. This size allows the MT-6MX to be installed in machine frames, between guard rails, behind equipment panels, and in positions where standard block-style sensors would not physically fit.

The mounting footprint is standard for the series, using through-hole or bracket mounting compatible with the range of Fotek MT series accessories.

The small housing does not compromise environmental protection — IP67 sealing is maintained through the compact form factor, ensuring the sensor operates correctly in environments with wash-down exposure, coolant mist, and dust accumulation that would compromise poorly sealed devices.

NPN & PNP Dual Output — Universal PLC Compatibility

Having both NPN and PNP outputs available simultaneously from the same receiver unit removes the sensor selection constraint imposed by PLC input card polarity.

In mixed-standard machine environments — common in Asian manufacturing facilities where Japanese NPN-standard machines and European PNP-standard machines operate side by side — a single MT-6MX stock item serves both without requiring separate NPN and PNP variants.

Wiring is straightforward: connect the brown wire to +24V DC supply, blue wire to supply common (0V).

For NPN output, the black wire connects to the PLC NPN input terminal and the output sinks current when the output is active. For PNP output, the white wire connects to the PLC PNP input terminal and sources current when active. 

Only one output needs to be connected in any installation; the unused output wire is insulated and left open.

FAQ

Q1: Does the MT-6MX emit visible or infrared light in through-beam mode?

The MT series uses modulated infrared or visible light depending on the specific variant. In through-beam applications at 6m range, the emitter projects its light beam — either infrared LED or visible red LED — toward the receiver.

The modulated light signal distinguishes the sensor's own beam from ambient light, preventing false triggering from sunlight or artificial lighting in the detection zone.

For applications where beam visibility is needed for alignment during installation, check the specific LED type on the sensor label or in Fotek's MT series documentation.

Q2: How are the emitter and receiver aligned at 6m range?

At 6m, small angular misalignment between emitter and receiver can direct the beam past the receiver face. Fotek MT series through-beam sensors use modulated LEDs with defined beam angles — typically a few degrees divergence.

For initial installation, align the emitter and receiver on a common axis using a spirit level and measurement, then power both units and adjust in small increments while monitoring the receiver's output indicator until the stability LED or signal strength indicator confirms maximum received signal. Lock both units with bracket hardware at that position.

Q3: Can the MT-6MX detect transparent objects such as glass or clear plastic film?

Standard through-beam sensors with infrared or red LED emitters detect transparent objects poorly — the light passes through rather than being blocked.

For transparent object detection (clear bottles, film, glass panels), a specialised through-beam sensor with polarised light or a specific transparent-object model is required. 

The MT-6MX is designed for opaque object detection and will not reliably detect targets that transmit more than approximately 70–80% of the beam.

Q4: What is the response time of the MT-6MX?

The MT series mini photo sensors have response times in the millisecond range, consistent with Fotek's photoelectric series.

For precise response time values applicable to the MT-6MX variant in your application — particularly for high-speed detection where the target passes the beam quickly — consult Fotek's MT series datasheet for the specific ON-time and OFF-time values, as these determine the minimum detectable target size at a given target speed.

Q5: The sensor includes polarity reversal protection — does this mean the supply wires can be swapped without damage?

Polarity reversal protection means the sensor survives brief connection of the supply in reverse polarity — it will not operate correctly with reversed wiring, but the protection circuit prevents permanent internal damage.

Normal operation requires correct polarity connection (brown to +V, blue to 0V). The protection is a safeguard against installation error during maintenance, not a licence to operate the sensor with reversed wiring.

Correct the polarity connection immediately if reversed; the protection circuit does not guarantee survival of sustained reversed supply.