Product Description

Omron E3S-CL2 — Distance-Settable Photoelectric Sensor with Metal Case, 5–500 mm

Standard diffuse-reflective photoelectric sensors have a well-known limitation: their detection point shifts depending on the colour and surface finish of the target object. A black rubber part and a white paper label at the same physical distance will produce different signal levels, potentially causing the sensor to miss one and detect the other. On a production line running mixed materials, this inconsistency creates false rejects and missed detections — both expensive problems.

The E3S-CL2 eliminates this limitation through triangulation-based distance setting. Detection is based on the geometric position of the reflected light spot on the sensor's receiver array, not the intensity of the returned signal. Objects at or closer than the set distance are detected regardless of their colour or surface reflectivity. Objects beyond the set distance — including background surfaces and conveyor structure — are reliably ignored. Black/white error is 10% maximum of the set distance across the full 50–500 mm setting range.

Add a zinc die-cast housing, IP67 protection, oil-resistant cable, and switch-selectable NPN/PNP output, and the E3S-CL2 covers the demanding end of industrial detection applications from food and beverage to machine tool environments.

Genuine Omron manufacture. Brand new sealed stock. In stock for immediate worldwide dispatch.

Technical Specifications

Parameter	Value
Model Number	E3S-CL2
Series	E3S-CL
Sensing Method	Distance-setting (triangulation) — Background Suppression (BGS)
Sensing Distance	5–500 mm
Setting Range	50–500 mm
Differential Travel (Hysteresis)	10% max of set distance
Black/White Error	10% max of set distance
Light Source	Infrared LED
Wavelength	860 nm
Power Supply Voltage	10–30 V DC (ripple p-p ≤10%)
Current Consumption	50 mA max
Output Type	NPN / PNP open collector (switch selectable)
Load Supply Voltage	30 V DC max
Load Current	0–100 mA
Residual Voltage (NPN)	1.2 V max (at 100 mA load)
Residual Voltage (PNP)	2.0 V max (at 100 mA load)
Operation Mode	Light-ON / Dark-ON selectable
Response Time	2 ms max
Sensitivity Setting	6-turn endless adjuster with indicator
Ambient Illuminance (Incandescent)	5,000 lux max
Ambient Illuminance (Sunlight)	10,000 lux max
Protective Circuits	Surge suppressor, output short-circuit protection, reverse polarity protection, mutual interference prevention
Protection Rating	IP67 (IEC) / NEMA 6P
Housing Material	Die-cast zinc
Lens Material	Methacrylic resin
Cable	Oil-resistant, 4 mm dia, 3-conductor, 0.2 mm² (AWG24), 2 m
Operating Temperature	−25 to +55°C
Storage Temperature	−40 to +70°C
Connection Type	Pre-wired (2 m cable)

Triangulation: How Distance-Setting BGS Actually Works

Most photoelectric sensors — whether through-beam, retroreflective, or diffuse-reflective — base their detection on signal intensity. The emitter sends out a beam of light; the receiver measures how much comes back. When that returned intensity crosses a threshold, the output switches. The problem is obvious: a shiny white surface at 200 mm returns more light than a matte black surface at 100 mm. Set the threshold for the black object at 100 mm and the white background behind it at 250 mm may trigger the sensor before the target ever arrives.

The E3S-CL2 works differently. It uses triangulation geometry — the same principle used in laser displacement sensors — but implemented in a compact photoelectric package. The emitter projects an infrared spot onto the target. The position of that reflected spot on the receiver's position-sensitive element shifts depending on the target's distance from the sensor: close targets deflect the spot to one side of the array; distant targets project it to the other. The sensor detects objects whose spot falls within the configured position window, and ignores anything — regardless of reflectivity — that falls outside it.

The practical consequence is that once you set the detection distance, objects at that distance or closer will be detected whether they are matte black rubber, mirror-finish stainless steel, translucent plastic, or white paper. The background behind the detection zone — the conveyor belt, the machine frame, the far wall — is simply not seen by the sensor, because its spot falls on the wrong part of the receiver array. This is what "background suppression" means in a triangulation sensor: physical geometry suppresses the background, not a software threshold.

Setting Range: 50–500 mm, 6-Turn Adjuster with Indicator

The E3S-CL2's detection distance is set using a 6-turn endless rotary adjuster with a built-in position indicator. The indicator shows where in the adjuster's travel range the current setting sits, allowing repeatable repositioning after replacement without needing to re-teach from scratch.

The setting range spans 50 to 500 mm — the full range at which the triangulation geometry produces reliable background rejection. Within this range, any target approaching from the background side will be detected at the set point, and objects beyond that point will be ignored.

Note the distinction between sensing distance and setting range: the sensing distance of 5–500 mm describes the closest and farthest points where any object can physically be detected; the setting range of 50–500 mm describes the span within which the background suppression threshold can be positioned. Objects closer than 50 mm will be detected regardless of where the adjuster is set — the triangulation geometry cannot suppress objects that close to the emitter.

NPN/PNP Output Selection: One Unit for Any PLC

Control system wiring conventions differ. European machine builders and many Siemens PLC applications use PNP (sourcing) sensor outputs; Japanese machine builders and many Omron and Mitsubishi PLC configurations expect NPN (sinking) inputs. Traditionally, stocking two sensor variants — one NPN, one PNP — was the practical solution for a panel shop serving both types of customer.

The E3S-CL2 carries a recessed output selection switch on the sensor body that toggles between NPN and PNP output mode. One catalog part number covers both wiring configurations. The switch is accessible with a small flat-blade screwdriver and is positioned to be adjustable during installation before the sensor is fully mounted, but not easily changed by vibration or incidental contact in service.

Light-ON / Dark-ON mode is also switch-selectable on the same operation panel, independent of the NPN/PNP selection. Light-ON (normally open equivalent) switches the output when the target is present and light is reflected back to the receiver. Dark-ON (normally closed equivalent) switches when the target is absent. Both modes use the same physical sensor and the same output circuit.

IP67 Metal Case with Oil-Resistant Cable: Built for Machine Tool Environments

The E3S-CL2's zinc die-cast housing with IP67 sealing means the sensor can be submerged to 1 metre depth for up to 30 minutes under IEC 60529 test conditions. In practical terms, this covers the full range of wash-down, coolant splash, and high-pressure cleaning exposure found in machine tool, food processing, and automotive assembly environments.

The oil resistance goes beyond the housing itself. The cable is constructed from oil-resistant vinyl specifically evaluated for resistance to cutting oils, hydraulic fluids, and machine lubricants. Omron validates the E3S-CL2's cable construction against immersion in relevant oil types at elevated temperature — standard vinyl cable insulation degrades, stiffens, and eventually cracks under sustained oil exposure; the oil-resistant formulation maintains flexibility and insulation integrity.

The die-cast zinc body also provides mechanical robustness against impacts and vibration that would crack or deform a plastic-bodied sensor. In environments where setup tools, workpieces, or robot end-effectors occasionally contact the sensor, metal construction substantially extends service life.

Built-In Protective Circuits

The E3S-CL2 integrates four protective circuits that reduce installation risk and field failure modes:

Surge suppressor — absorbs voltage transients on the supply and output lines caused by inductive switching from solenoid valves, motor contactors, and relay coils sharing the same power supply. Without this, transients can exceed the sensor's internal circuit voltage ratings and cause immediate or accelerated failure.

Output short-circuit protection — limits output current if the load circuit is accidentally short-circuited, preventing transistor damage. The sensor survives a wiring error that would destroy an unprotected open-collector output stage.

Reverse polarity protection — prevents damage if the supply polarity is accidentally reversed during installation. Particularly useful during commissioning when 24V DC wiring is being connected and polarity errors are more likely.

Mutual interference prevention — multiple E3S-CL sensors mounted in close proximity on the same machine section will not trigger each other's receivers. The interference prevention circuit allows adjacent sensors to operate without the output instability or false detections that unprotected sensors would produce when their beams overlap.

Two Status Indicators: Stability and Output, at a Glance

The E3S-CL2 carries two LED indicators visible from the cable entry side of the sensor:

The green stability indicator shows that the received signal level has sufficient margin above the detection threshold. Green steady means the sensor is receiving a stable signal — the target is clearly detected or clearly absent, with adequate margin. If the green LED is not lit during what should be a stable state, the operating margin is marginal and the sensor installation should be reviewed for alignment, contamination, or target surface changes.

The orange output indicator shows the current state of the control output — lit when the output is active. This is the basic commissioning indicator: move a target through the detection zone and watch the orange LED switch at the configured detection point.

Together, the two indicators allow on-the-spot assessment of whether a sensor is operating with confidence or is at the edge of its performance envelope — without connecting a meter or diagnostic tool.

Frequently Asked Questions

Q: What is the difference between E3S-CL1 and E3S-CL2?

A: Both use the same triangulation distance-setting principle in the same metal housing. The key differences are in sensing range and oil resistance. The E3S-CL1 covers 5–200 mm sensing distance with a setting range of 40–200 mm, has a tighter hysteresis specification of 2% maximum at 200 mm, and uses a standard (non-oil-resistant) cable. The E3S-CL2 extends the range to 5–500 mm with a 50–500 mm setting range, has a hysteresis of 10% maximum of the setting distance, and uses an oil-resistant cable. Choose the E3S-CL1 for shorter-range applications requiring the tightest hysteresis; choose the E3S-CL2 for longer-range detection or oil-environment installations.

Q: Can the E3S-CL2 detect transparent or translucent objects?

A: Detection of transparent objects like glass or clear plastic depends on whether sufficient infrared light is reflected back to the sensor at the set distance. Highly transparent materials reflect very little IR light — the beam passes through — making detection unreliable with standard background suppression sensors. For transparent object detection, dedicated sensors using polarised light or laser-based detection are more appropriate. The E3S-CL2 is optimised for opaque objects with varying surface colours and finishes.

Q: How do I switch between NPN and PNP output modes?

A: The output selection switch is a small recessed slider on the sensor body, accessible with a 0.5–1 mm flat-blade screwdriver. Moving the switch to position "N" selects NPN open collector output; position "P" selects PNP open collector output. The switch should be set before installation. Note that altering output mode after the sensor is wired into a live circuit without first disconnecting the load can cause brief output transients — set the mode before connecting the load wiring.

Q: What is the typical application for the E3S-CL2 compared to a standard diffuse reflective sensor?

A: The E3S-CL2 is the preferred choice wherever target objects vary in colour, surface finish, or material — and wherever there are background objects (conveyor surfaces, product guides, walls) that must not be falsely detected. Typical applications include part presence detection on conveyors running mixed product, label detection on packages where the underlying surface differs from the label, object counting on machinery where the machine frame is behind the target, and any detection task where a conventional diffuse sensor's sensitivity requires adjustment every time the product changes.

Q: What is the response time of the E3S-CL2, and is it fast enough for high-speed applications?

A: Response time is 2 ms maximum — the time between a change at the sensing face and the corresponding change at the output terminal. At 2 ms, the sensor can reliably detect objects passing at up to 250 mm/s at the minimum detectable object size of the sensor. For higher-speed detection requirements — small parts on fast conveyors, high-speed indexing — the 2 ms response may limit the minimum detectable object size at a given conveyor speed, and a faster sensor should be considered.

Q: Is the E3S-CL2 compatible with 12V DC power supplies?

A: Yes. The supply voltage range is 10–30 V DC, which covers both 12V DC nominal supplies (which typically deliver 11–13V) and 24V DC nominal industrial supplies (typically 21.6–26.4V). Both NPN and PNP output modes are compatible with standard 12V and 24V PLC input modules.

Q: What does the "Light-ON" vs "Dark-ON" mode mean, and which should I use?

A: Light-ON (L) switches the output ON when the target is present and reflecting light back to the sensor. This is equivalent to normally open (NO) contact behaviour — the output activates on detection. Dark-ON (D) switches the output ON when the target is absent and no light is reflected. This is equivalent to normally closed (NC) contact behaviour — the output is energised at rest and de-activates on detection. For most part-present detection applications, Light-ON is the standard choice. Dark-ON is used when the application logic requires an energised output during the absence of the target, or for fail-safe architectures where a broken cable (which de-energises the output) and a missing part produce the same response.

E3S-CL2 Genuine Omron E3SCL2 Photoelectric Sensor Switch