What Is a 90-Degree Metal Cylindrical Photoelectric Sensor? Types and Selection Criteria
A 90-degree metal cylindrical photoelectric sensor sends its light from the side of an M18 metal housing, perpendicular to its axis, instead of from the end.
A 90-degree metal cylindrical photoelectric sensor is a photoelectric sensor with an M18 threaded metal housing that sends its light from the side of the housing, perpendicular to its axis, instead of from the end. A straight-optics M18 sensor needs depth behind it for the housing length and the cable; a 90-degree model is laid parallel to the mounting surface. It is used to detect objects inside machines, along conveyor edges and in tight spaces.
Types
| Type | Operation | Range in the catalog |
|---|---|---|
| Diffuse reflective | Light is reflected by the object back into the same housing; nothing is mounted opposite | 40 cm |
| Through-beam | Emitter and receiver are in separate housings; the object interrupts the beam between them | 20 m |
According to the product specifications, the Lanbao PR18TG models in the catalog are powered by 10–30 V DC; the receivers provide NO and NC outputs together. In the code, BC stands for diffuse reflective and TM for through-beam; DNR stands for NPN and DPR for PNP output. Models with the -E2 suffix have an M12 connector, those without it a cable outlet. This series has no retroreflective model.
Selection criteria
- Light exit direction: The lens is on the side face of the housing. Because the threaded housing can turn in the hole, point the lens at the object (at the opposite unit for through-beam) and tighten the nuts afterwards.
- Sensing mode: Choose diffuse reflective if nothing can be mounted opposite, and through-beam if cables can be run to both sides. The 40 cm is measured on a white reference surface; it is shorter on dark, matt objects.
- Output: Choose PNP (DPR) if the PLC input expects a positive signal and NPN (DNR) if it expects a negative signal.
- Connection: A connector (-E2) model can be replaced without removing the cable; an M12 connection cable is needed separately. In the catalog, the NPN through-beam receiver is available only with a cable (PR18TG-TM20DNR).
- Housing: If the risk of impact is low and a retroreflective type is needed, look at the plastic-body PR18TGS series with the same optical layout; it also includes a 3 m retroreflective model.
Common mistakes
- Fitting it in place of a straight-optics sensor: It fits the same M18 hole, but the light exits from the side and does not face the object; plan the mounting direction from the start.
- Tightening the nuts before alignment: If the housing turns under vibration, the beam drifts; a through-beam receiver loses the signal.
- Buying only one half of a through-beam pair: PR18TG-TM20D and TM20D-E2, with "Çıkış Işık Kaynağı" (light source output) in their names, are emitters only; order them with an NPN or PNP receiver from the same series.
- Shiny background: With the diffuse reflective type, shiny sheet metal or a white wall within 40 cm triggers the output with no object present.
Note: The category is for metal housings, but the product names include "Plastik" (plastic). If you need a specific housing material, confirm it with the product code before ordering.
Standard
Photoelectric sensors fall under IEC 60947-5-2, the standard that defines proximity switches.
Products in the catalog
The 90-Degree Metal Cylindrical Photoelectric Sensors category lists 9 active products from Lanbao (PR18TG series):
| Type | Range | Models |
|---|---|---|
| Diffuse reflective, NPN NO+NC | 40 cm | BC40DNR, BC40DNR-E2 |
| Diffuse reflective, PNP NO+NC | 40 cm | BC40DPR, BC40DPR-E2 |
| Through-beam emitter | 20 m | TM20D, TM20D-E2 |
| Through-beam receiver, NPN NO+NC | 20 m | TM20DNR |
| Through-beam receiver, PNP NO+NC | 20 m | TM20DPR, TM20DPR-E2 |
Plastic-body DC models are under 90-Degree Plastic Cylindrical Photoelectric Sensors, models that run on mains voltage under AC Two-Wire 90-Degree Plastic Cylindrical Photoelectric Sensors, and straight-optics types under Cylindrical Photoelectric Sensors.
Frequently asked questions
What is the difference between a 90-degree and a straight-optics photoelectric sensor?
In a straight-optics sensor the light exits from the end of the housing, along its axis; in a 90-degree model it exits from the side, perpendicular to the axis. The sensing principle is the same; the difference is mounting: a 90-degree model is laid parallel to the surface where there is no room along the axis in front of the sensor.
Which parts does a 90-degree through-beam sensor need?
One emitter (TM20D or TM20D-E2) and one receiver (TM20DNR, TM20DPR or TM20DPR-E2). The two are aligned so that their lenses face each other.
Should I choose a metal or a plastic 90-degree sensor?
A metal housing is more durable where there is a risk of impact and vibration. If a retroreflective type is needed, choose the plastic PR18TGS series; the metal PR18TG series has no retroreflective model.