Diffuse photoelectric proximity sensor | 1-600mm | 10-36VDC | PNP | NO | M12 | SensoPart | FT18 R-PSL4 | 704-21000

SensoPart FT 18 R-PSL4 photoelectric proximity sensor | 1–600 mm | 10–36 V DC | PNP NO | 200 mA | M12 | 704-21000

SensoPart FT 18 R-PSL4 (704-21000) – an industrial optical proximity sensor (diffuse-reflective photoelectric sensor) designed for detecting objects without mechanical contact. The sensor operates on the principle of light reflected from the object's surface and features an adjustable detection distance of 1–600 mm. It is powered by 10–36 V DC and has a PNP normally open (NO) transistor output with a maximum load current of 200 mA. The sensor connects via an M12 × 1 four-pin connector, while sensitivity is adjusted using an integrated potentiometer. Green and yellow LED indicators allow monitoring of the sensor's operating reserve and switching status.

Key point:
In automated systems, an object often needs to be detected without physically touching it. The SensoPart FT 18 R-PSL4 optical proximity sensor detects light reflected from the surface of the monitored object and transmits a PNP signal to the control system. The integrated potentiometer allows the required detection distance to be set, while the LED indicators simplify sensor adjustment and diagnostics. This design is suitable for industrial automation processes where non-contact object presence detection is required.

Why is this sensor useful?
FT 18 R-PSL4 allows objects to be detected without contact, the detection distance to be adjusted, and a digital signal to be transmitted to an automatic control system. Integrated sensitivity adjustment and two LED indicators simplify installation, adjustment and diagnostic work. The 10–36 V DC supply, PNP NO output and M12 connector allow the sensor to be integrated into compatible industrial automation systems.

• Non-contact object detection – objects are detected by light reflected from their surface.
• Adjustable detection distance – 1–600 mm range, adjustable using the integrated potentiometer.
• PNP NO output – normally open transistor output for transmitting a control signal.
• Maximum 200 mA output current – permitted load of the transistor output.
• 10–36 V DC supply – intended for compatible DC automation systems.
• Switching frequency up to 100 Hz – switching of object detection signals within the specified frequency range.
• Integrated potentiometer – for adjusting the detection distance according to the object and mounting conditions.
• Green LED indicator – indicates sufficient sensor operating reserve.
• Yellow LED indicator – indicates the sensor output switching status.
• M18 × 1 mounting thread – for mechanical fastening of the sensor.
• M12 four-pin connector – for electrical connection of the sensor.
• Freely selectable mounting position – the sensor can be installed according to the equipment design.

• In industrial automation systems for object presence detection
• At object detection points on conveyors and transport lines
• In production equipment for checking the presence of parts
• In automatic assembly and technological process control systems
• In packaging and sorting equipment
• In machinery work areas where non-contact detection is required
• In electronic control systems with PNP sensor inputs
• In OEM industrial equipment manufacturing and modernization projects

For example, on an automated transport line it is necessary to determine whether a part has reached the intended position. The FT 18 R-PSL4 sensor is installed so that its optical section is directed toward the part detection zone. The required detection distance is set using the integrated potentiometer, while the green LED indicator is used to assess reliable operating reserve. When the part is detected, the PNP NO output is activated, and its signal can be processed by a compatible programmable logic controller (PLC). The yellow LED indicator allows the switching status to be checked. In this way, the presence of the part is detected without mechanical contact.

• ⚡ Disconnect the power supply before installing or connecting the sensor.
• Use only a 10–36 V DC supply voltage.
• The sensor must not be connected directly to a 230 V AC mains supply.
• The maximum PNP output load current must not exceed 200 mA.
• Use the M18 × 1 threaded section of the sensor and suitable fasteners for mounting.
• Do not exceed the maximum mounting nut tightening torque of 20 Nm.
• The sensor can be mounted in various positions, but the optical section must be correctly directed toward the object to be detected.
• Avoid contamination of the optical window with dust, liquids and other deposits.
• Install the sensor so that, as far as possible, dirt and liquids do not accumulate on the optical surface.
• Ensure access to the optical window for cleaning.
• Clean with a soft cloth slightly moistened with isopropyl alcohol or soapy water.
• Adjust the detection distance using the integrated potentiometer. The initial setting is the maximum distance.
• If necessary, reduce the detection distance by turning the potentiometer counterclockwise.
• For reliable operation, the green operating reserve LED indicator should be illuminated.
• The yellow LED indicates the switching output status.
• Make electrical connections according to the original product wiring diagram and pin markings.
• The sensor is not intended for personnel safety functions. It must not be used as a safety device for protecting people from hazardous machine movements or other risks.

The sensor has an M12 × 1 four-pin connector. Electrical connection is made according to the pin numbering and wire colour coding.

Pin	Wire	Function
1	BN – brown	+UB, positive supply
2	–	–
3	BU – blue	−UB, negative supply
4	BK – black	PNP NO switching output

Note: before connection, check the original manufacturer's wiring diagram, connector pin numbering and the compatibility of the controller input with the PNP output.

Quick selection guide

How does the FT 18 R-PSL4 sensor operate?
The sensor detects an object using light reflected from its surface. When an object enters the detection zone, the PNP switching output is activated.

What is the maximum detection distance?
The maximum nominal detection distance is 600 mm. It is specified using a white reference surface with 90 % reflectance.

Can the sensor detection distance be adjusted?
Yes. The detection distance is adjusted using the integrated potentiometer. The initial setting is the maximum, and the distance can be reduced by turning the potentiometer counterclockwise.

What does PNP NO output mean?
PNP means a transistor output that supplies a positive-potential signal to the load when activated. NO means normally open switching function.

What is the sensor supply voltage?
The sensor operates from 10 to 36 V DC.

What is the maximum output current?
The maximum load current of the PNP transistor output is 200 mA.

What does the green LED indicator show?
The green LED indicator shows the sensor operating reserve. For reliable detection, it should be illuminated.

What does the yellow LED indicator show?
The yellow LED indicator shows the sensor switching output status.

Can the sensor detect dark objects?
Detection depends on the reflective properties of the object's surface. For darker or less reflective objects, the detection distance may be shorter than the nominal distance.

What electrical connection is used?
The sensor has an M12 × 1 four-pin connector. Pins 1 and 3 are used for the power supply, while pin 4 is used for the PNP output.

What is the mounting thread?
The sensor is mounted using an M18 × 1 threaded section. Two mounting nuts are included.

What is the maximum mounting nut tightening torque?
The maximum tightening torque is 20 Nm.

How should the sensor's optical surface be cleaned?
A soft cloth slightly moistened with isopropyl alcohol or soapy water is recommended. Dirt accumulated on the optical window can reduce the detection distance.

Is this sensor suitable for personnel safety systems?
No. FT 18 R-PSL4 is not intended for functions related to personnel safety and cannot replace certified safety sensors.

SensoPart FT 18 R-PSL4 | 704-21000 | optical proximity sensor | 1–600 mm | PNP NO

Industrial diffuse-reflective optical sensor for non-contact object detection. Adjustable 1–600 mm detection distance, 10–36 V DC supply, PNP NO transistor output, maximum 200 mA load current and switching frequency up to 100 Hz. M18 × 1 mounting thread, M12 four-pin connector, integrated adjustment potentiometer and green and yellow LED indicators. Suitable for automated production, transport and industrial equipment control systems.