Diffuse Sensor with Background Suppression
Part Number: 50129400
Model: HT5.1/4
Manufacturer: Leuze electronic GmbH + Co. KG
Series: 5
Operating Principle: Diffuse reflection with background suppression
Light Source: LED, red, 645 nm, pulsed
Focus: Fixed at 200 mm
Light Spot Geometry: Round
LED Group: Exempt (EN 62471)
Black-White Error: < 15% up to 200 mm
Operating Range (typical):
White (90% reflectivity): 5–400 mm
Gray (18%): 10–300 mm
Black (6%): 15–200 mm
Adjustment Range: 15–400 mm
Beam Path: Focused
Supply Voltage: 10–30 V DC
Residual Ripple: 0–15% of UB
Open-circuit Current: 0–15 mA
Protective Circuitry: Polarity reversal protection, short-circuit protected
Protection Class: III
Degree of Protection: IP67
Switching Output: 1x PNP, Light Switching
Switching Current (max): 100 mA
Switching Voltage:
High: ≥ UB – 2 V
Low: ≤ 2 V
Switching Frequency: 1,000 Hz
Response Time: 0.5 ms
Readiness Delay: 300 ms
Cable Type: 3-wire, PUR sheath
Length: 2,000 mm
Conductor Colors:
Brown: V+
Blue: GND
Black: OUT 1
Wire Cross Section: 0.2 mm²
Dimensions (W x H x L): 11.4 mm x 32.1 mm x 17.8 mm
Weight: 50 g
Housing Material: Plastic (PC-ABS)
Lens Cover: PMMA
Mounting: Two M3 threaded sleeves or optional bracket
LED Indicators:
Green (continuous): Power on
Yellow (continuous): Object detected
Control Element: Multiturn potentiometer for range adjustment
Operating Temperature: –40°C to +60°C
Storage Temperature: –40°C to +70°C
Approvals: c UL US
Standards: IEC 60947-5-2
Customs Tariff No.: 85365019
ECLASS/ETIM Classifications: Multiple versions (ECLASS 5.1.4 to 15.0, ETIM 5.0 to 10.0: EC002719)
Mounting Brackets:
50118542: BT 200M.5 (adjustable, L-shape, stainless steel)
50124651: BT 205M-10SET (rigid, L-shape, metal)
50060511: BT 3 (rigid, L-shape, metal)
Rod Mounts:
50117829: BTP 200M-D12 (adjustable/protective, for 12 mm rod, metal)
50117255: BTU 200M-D12 (adjustable, sheet-metal mounting, metal)
Application Limitation: Not for personnel safety applications
Service Life: ~100,000 h at 25°C ambient
Response Time Note: Use ~5 kΩ ohmic load for short decay times
UL Application: Use only with Class 2 circuits and UL-listed cable assemblies (30V, 0.5A min.)
12. 🛠 Troubleshooting Points for HT5.1/4 Diffuse Sensor
No green LED (power indicator):
Check if 10–30 V DC power is supplied.
Verify wiring polarity (brown = +V, blue = GND).
Measure voltage at sensor terminals.
Intermittent sensor function:
Check for loose or corroded connections.
Inspect cable for cuts, abrasions, or bending stress.
Measure supply ripple (should be <15%).
Sensor gets hot:
Ensure power supply does not exceed 30 V DC.
Check ambient temperature (must be < 60°C).
No yellow LED when object is present:
Object may be outside detection range.
Check if object color is too dark (e.g., <6% reflectivity).
Adjust detection distance using potentiometer.
Yellow LED ON but no output signal:
Load current may exceed 100 mA (check with multimeter).
Output may be shorted; verify load circuit.
Output remains ON even with no object:
Background might be highly reflective and close.
Adjust background suppression using potentiometer.
False switching (flickering output):
Check for shiny, moving background behind object.
Use shield or reposition sensor to avoid background interference.
Object not detected:
Ensure object is within 5 mm to 400 mm range.
Check angle of incidence – ensure perpendicular approach.
Sensor detects background instead of object:
Adjust suppression range away from background.
Use matte/low-reflectivity backdrop if possible.
Short detection range:
Lens may be dirty or scratched – clean with soft cloth.
Check if sensor was mounted too far from object.
Long detection range but poor accuracy:
Re-calibrate using adjustment screw.
Replace with a focused beam variant if precision is needed.
Sensor physically unstable:
Ensure M3 screw mounts are properly fixed.
Use vibration damping brackets (e.g., BT 200M).
Sensor easily knocked out of alignment:
Consider using a rod mount (e.g., BTP 200M-D12).
Tighten all mounting screws with thread-lock if needed.
Wrong orientation for detection:
Ensure sensor is facing reflective surface directly.
Use alignment tools or laser pointer for precise setup.
Condensation or fog on lens:
Install in an enclosure or use lens heater if in humid area.
Avoid direct water spray; IP67 is not waterproof under pressure.
Dirt/oil buildup on lens:
Schedule regular cleaning with lint-free cloth and isopropyl alcohol.
Sensor reacts slowly in cold temperatures:
Check for slow LED response below 0°C; warm-up time may help.
Electrical noise affecting output:
Check for nearby high-frequency devices or motors.
Use shielded cables or ferrite core filters on power lines.
Ambient light interference:
Although sensor uses modulated red light, excessive sunlight/glare can confuse readings—use shade/cover.
Potentiometer has no effect:
It may be over-rotated; reset to midpoint and retry.
Ensure multiturn potentiometer is turning (feel for resistance).
Detection changes after power cycle:
Sensor has no memory – settings must be manually adjusted again if mechanically altered.
Inconsistent output in similar conditions:
Object reflectivity may vary; test using standard calibration targets (white/gray/black cards).
Incorrect load wiring:
Ensure load is connected between black (output) and ground (blue).
For inductive loads (e.g., relays), add a freewheeling diode.
Overloaded output:
Ensure max 100 mA load; otherwise transistor may fail.
PNP output doesn't work with NPN PLC input:
Mismatch of logic levels – use a relay or opto-isolator.
Shared power supply noise:
Use separate power lines for sensor and high-inductive loads.
Green LED OFF, yellow LED blinking:
Sensor booting or unstable supply.
Wait 300 ms or check power integrity.
Green LED ON, no yellow LED even with close object:
Potentiometer set beyond max distance or object not reflective enough.
Both LEDs OFF:
Total power failure or internal sensor fault.
Green LED ON, but sensor behaves erratically:
Possible internal damage – replace the unit or send for inspection.
Sensor works on test bench but not in machine:
Check machine's ground potential, electromagnetic noise, or signal load mismatch.
Sensor gets damaged repeatedly:
Check for incorrect voltage spikes or mechanical shock.
Add surge protector or mechanical shield.
Sensor misaligned after maintenance:
Use permanent marker or bracket index to restore original position.