FESTO SME-8M-DS-24V-K-0.3-M8D Cylinder Magnetic Switch

Part-No.: 543861

Product: T-slot cylinder magnetic switch, magnetic-reed contact, 3-wire Normally-Open (NO), 0.3 m cable with M8 3-pin male connector, screw-lock mounting, compatible with FESTO T-slot cylinders.

Model Decoding SME-8M-DS-24V-K-0.3-M8D

Field	Description
SME	Cylinder magnetic proximity sensor series
8M	T‑slot mounting, insert into T‑slot from top, screw‑fastened (fits DSBC, ADN, ADVU, DNC and other T‑slot profile cylinders)
DS	3‑wire Normally‑Open NO, bipolar reed‑contact output (compatible with both NPN and PNP PLC inputs)
24V	Rated voltage DC24V; operating range DC5‑30V / AC5‑30V
K	Oil‑resistant cable suitable for energy‑chain applications
0.3	Cable length 0.3 m
M8D	M8‑A‑coded male connector with threaded locking (distinguished from snap‑in M8 connectors)

Core Electrical & Mechanical Specifications

Sensing principle: Magnetic-reed

Output: 3-wire Normally-Open NO, bipolar contact, no short-circuit protection, no reverse-polarity protection

Max. load current: 500 mA direct load; 80 mA when using mounting accessories

Max. switching capacity: DC 10 W; AC 10 VA

Voltage drop: 1.17 V

IP rating: IP65 / IP68

Operating temperature: -40 ℃ ~ +70 ℃; energy-chain cable: -5 ℃ ~ +70 ℃

Weight: 8.9 g

Status indicator: Built-in LED; LED illuminates upon detection of cylinder piston magnet ring

Cable: Oil-resistant, energy-chain-rated for > 5 million bending cycles

⚠️Important Note: No short-circuit or reverse-polarity protection. Mis-wiring may permanently destroy the sensor.

Pin Assignment M8-A-coded 3-pin Male Connector

1-Brown: Power + (5-30 V)

3-Blue: 0 V GND

4-Black: Signal output NO

Compatible Cylinders (T-slot)

✅Supported: ADVU, ADN, DSBC, DNC, DSNU-K, DRRD, DGST and other T-slot profile cylinders

❌Not supported: Round non-slotted cylinders, legacy S-slot / C-slot cylinders; use SME-8 / SMT series for these cylinder types.

Installation Guidelines

Insert sensor from top into cylinder T-slot, tighten top M2 locking screw; do not strike housing forcibly.
Position adjustment: Slide sensor until LED lights up when piston magnet ring passes, fine-tune position then tighten screw.
Reed switches exhibit hysteresis: Switch-trigger positions differ by several mm for forward / reverse piston travel; reserve mechanical margin for high-speed cylinders.
0.3 m short cable; must pair with FESTO NEBU-series M8 extension cables.
Do not directly drive large solenoid coils; connect free-wheeling diodes across inductive loads for surge suppression.

Quick Reference for Similar Models

Part‑No.	Full Model	Cable	Connector	Output
543861	SME‑8M‑DS‑24 ‑K‑0.3‑M8D	0.3 m	M8 threaded male	3‑wire NO
543862	SME‑8M‑DS‑24 ‑K‑2.5‑M8D	2.5 m	M8 threaded male	3‑wire NO
543863	SME‑8M‑DO‑24V ‑K‑0.3‑M8D	0.3 m	M8 threaded male	3‑wire NC
543874	SME‑8M‑ZS‑24V ‑K‑2.5‑OE	2.5 m	Open‑end bare wires	2‑wire PNP NO

Compatible Accessories

M8 extension cables: NEBU-M8G3-K-0.5-M8G3 / 1 m / 2 m /5 m
Domestic compatible alternative: T-slot magnetic-reed switch, M8-3-pin NO, oil-resistant cable
Spare parts: No separate spare components; replace complete unit upon failure.

Typical Application Scenarios

Position detection for automated tooling cylinders: Clamping cylinders, lifting cylinders; forward / rear position feedback to PLC. M8 plug-in enables quick disassembly-assembly for equipment maintenance.
Pusher / stopper cylinder position feedback for packaging machinery; 0.3 m short cable plus extension cable reduces scattered internal wiring.
Pneumatic gripper cylinders for robot end-effectors: ADN / ADVU compact cylinders, narrow installation space; oil-resistant cable for oily shop-floor environments.
Pneumatic fixture / pneumatic gate limit detection on machine tools; wide temperature range -40~70 ℃ suitable for low-temperature equipment.

Limitations

Reed-contact service life inferior to Hall-effect sensors; not suitable for ultra-high-frequency millions-of-cycle operation. Use SMT-8 Hall-effect series for high-speed applications.
No reverse-polarity or short-circuit protection; strictly verify pin-out before wiring.
0.3 m very short cable; M8 extension cables must be included in BOM during project design.

Troubleshooting

LED does not illuminate: No supply voltage; sensor misaligned relative to piston magnet ring; cylinder without built-in magnet ring.
LED lit but no PLC input signal: Incorrect wiring; burned-out internal contacts due to excessive load; missing surge suppression for inductive loads.
Signal flickering: Strong nearby magnetic-field interference; loose sensor mounting screw.

Customs HS-code reference: 8543709990, magnetic proximity sensor.

SME-8M-DS-24V-K-0.3-M8D (Part-No.543861) BOM Accessories, SMT-8 Comparison, Specification Text

Critical Reminder: This sensor part-number 543861 is identical to the MS6-LFR air-service unit part-number. Always specify full model in BOM; part-number-only ordering will cause wrong-part procurement.

NEBU-series M8 Extension Cable BOM List

Sensor integral cable length only 0.3 m, M8-A-coded 3-pin male, requires downstream M8 female-end extension cable to PLC terminal blocks.

Model	Part‑No.	Length	Construction	Application
NEBU‑M8G3‑K‑0.5‑LE3	541328	0.5 m	M8 female to bare wires	Short in‑machine wiring
NEBU‑M8G3‑K‑1‑LE3	541329	1 m	M8 female to bare wires	Most‑common standard length
NEBU‑M8G3‑K‑2‑LE3	541330	2 m	M8 female to bare wires	Medium‑distance routing
NEBU‑M8G3‑K‑5‑LE3	541331	5 m	M8 female to bare wires	Long‑distance routing

Cable notes: K = PUR energy-chain-rated oil-resistant cable; LE3 = 3-core; M8G3 = M8 female 3-pin; tightening torque 0.2 Nm, avoid over-torque thread damage.

Pin mapping: Brown 1(+24V), Blue 3(GND), Black 4(Signal output).

Selection Tips:

1) Fixed installation: standard cable; moving / energy-chain installation must select -K energy-chain type.

2) For M8-interface PLC I/O modules, select dual-ended plug cable: `NEBU-M8G3-K-1-M8G3`.

3) Sensor has no short-circuit / reverse-polarity protection. BOM recommendation: fit free-wheeling diodes across inductive solenoid loads.

SME-8M (Reed) vs SMT-8M (Magneto-Resistive Hall-Effect) Comparison

SME-8M-DS-24V-K-0.3-M8D: mechanical reed contacts; SMT-8M: solid-state magneto-resistive, no mechanical contacts.

Comparison Item	SME‑8M‑DS‑24V‑K‑0.3‑M8D (Reed)	SMT‑8M‑PS‑24V‑K‑0.3‑M8D (Hall‑effect PNP)
Sensing Principle	Magnetic‑reed mechanical contact	Magneto‑resistive semiconductor, contact‑free
Power Supply	DC5‑30V / AC5‑30V, AC‑DC universal	DC10‑30V DC‑only
Output Type	Bipolar 3‑wire NO, NPN / PNP compatible	Fixed PNP / NPN
Protection Features	No short‑circuit, no reverse‑polarity protection	Short‑circuit & reverse‑polarity protected
Max. Switching Frequency	≤140 Hz	≤1000 Hz, superior high‑frequency performance
Mechanical Service Life	~10 million cycles; contact erosion risk under high‑frequency shock	Virtually wear‑free for high‑cycle high‑speed operation
Leakage Current	Near‑zero	Minor leakage current present
Temperature Range	‑40~+70 ℃	‑25~+70 ℃
Cost	Lower	Higher
Recommended Application	Low‑speed tooling, cost‑sensitive, occasional AC‑loop usage	High‑speed cylinders, high‑cycle 24/7 production lines, priority on reliability

Selection Guidance:

✅Choose SME-8M: General low-speed tooling, cost-optimized, occasional AC-circuit application.

✅Choose SMT-8M: High-speed reciprocation, high-cycle, 24-hour continuous-run automation lines; prefer Hall-effect type.

Copy-Ready BOM / Specification Descriptions

BOM Item Description (direct copy-paste)

Magnetic proximity sensor; Model: SME-8M-DS-24V-K-0.3-M8D; Part-No.:543861; Brand FESTO; T-slot cylinder mounting; magnetic-reed, 3-wire Normally-Open NO; DC5-30V/AC5-30V; cable length 0.3 m, M8-A-coded 3-pin male connector; IP65/IP68; oil-resistant energy-chain-suitable cable; compatible with ADVU/ADN/DSBC/DNC T-slot profile cylinders.

Specification-document Paragraph (equipment technical documentation)

Cylinder position feedback adopts FESTO SME-8M-DS-24V-K-0.3-M8D magnetic switch, bipolar magnetic-reed-contact output supporting 5-30 V AC/DC; top-insert T-slot mounting with screw locking; built-in status-indicating LED; IP65/IP68 protection rating; 0.3 m cable with M8-A-coded 3-pin male plug, extended via NEBU-series M8 cables to PLC digital-input modules. Sensor provides no short-circuit or reverse-polarity protection; wiring strictly follows defined pin-out. Free-wheeling surge-suppression components are required for inductive loads. Used for piston-end-position detection of clamping, lifting and stopper cylinders.

On-site Installation-Commissioning & Additional Troubleshooting Notes
Installation: Insert into T-slot from top, tighten M2 screw with moderate torque to prevent housing cracking; fine-tune position until yellow LED activates upon magnet-ring passage, then lock screw.
Reed-switch hysteresis: Several mm offset between forward-travel and reverse-travel trigger points; reserve mechanical stroke margin for high-speed cylinders.
Never directly drive solenoid-valve coils; fit free-wheeling diodes across coils to avoid reed-contact burnout.
Fault: LED ON but no PLC input → check wiring; burned-out contacts due to overload; missing inductive-load surge suppression.
Signal chattering: Loose sensor mounting screw; nearby strong magnetic interference; demagnetized cylinder piston magnet ring.
Domestic-Alternative Reference Description

Domestic-alternative specification: T-slot magnetic-reed switch, 3-wire Normally-Open NO, M8-A-coded 3-pin male plug, 0.3 m PUR oil-resistant cable, IP67, DC5-30 V, compatible with FESTO T-slot cylinders.

SME-8M Full-Series Model List + NPN / PNP PLC Wiring

Basics: SME-8M: T-slot magnetic-reed switch; DS = 3-wire NO; DO = 3-wire NC; ZS = 2-wire PNP NO; M8D = M8-A male plug; OE = open-end bare-wire; K = energy-chain-rated PUR oil-resistant cable.

Target device: SME-8M-DS-24V-K-0.3-M8D｜Part-No.543861

SME-8M Complete Model List

① M8D Plug-in Versions (M8-A-coded male, 3-pin, short 0.3 m cable, widely-used for engineering)

Part‑No.	Full Model	Output Function	Cable	Connector
543861	SME‑8M‑DS‑24V‑K‑0.3‑M8D	3‑wire NO	0.3 m energy‑chain K	M8D male
543863	SME‑8M‑DO‑24V‑K‑0.3‑M8D	3‑wire NC	0.3 m energy‑chain K	M8D male
543862	SME‑8M‑DS‑24V‑K‑2.5‑M8D	3‑wire NO	2.5 m energy‑chain K	M8D male
543864	SME‑8M‑DO‑24V‑K‑2.5‑M8D	3‑wire NC	2.5 m energy‑chain K	M8D male

② OE Open-End Bare-Wire Versions (direct cable outlet without plug, for internal machine wiring)

Part‑No.	Full Model	Output Function	Cable Length	Connector
543865	SME‑8M‑DS‑24V‑K‑2.5‑OE	3‑wire NO	2.5 m	Open‑end OE
543866	SME‑8M‑DO‑24V‑K‑2.5‑OE	3‑wire NC	2.5 m	Open‑end OE
543867	SME‑8M‑DS‑24V‑K‑5.0‑OE	3‑wire NO	5.0 m	Open‑end OE
543868	SME‑8M‑DO‑24V‑K‑5.0‑OE	3‑wire NC	5.0 m	Open‑end OE
543874	SME‑8M‑ZS‑24V‑K‑2.5‑OE	2‑wire PNP NO	2.5 m	Open‑end OE

Suffix Definitions

DS: 3-wire bipolar Normally-Open NO (works with NPN / PNP PLC inputs)

DO: 3-wire bipolar Normally-Closed NC

ZS: 2-wire PNP Normally-Open NO

K: PUR energy-chain-rated oil-resistant cable; non-K = standard PVC cable

M8D: M8-A-coded threaded-lock male connector

OE: Open-end bare-wire termination

Common Electrical Characteristics: Magnetic-reed contact, no short-circuit / reverse-polarity protection; DC5-30V / AC5-30V; IP65-IP68.

SME-8M-DS-24V-K-0.3-M8D Wiring

M8-A 3-pin male pin-assignment

1 Brown: Power + DC24V

3 Blue: PowerGND 0 V

4 Black: Signal output (reed contact)

SME-8M-DS uses bipolar reed-contact switching. It is a mechanical switch element; not inherently NPNor PNP-type. Logic is determined by PLC input common COM wiring.

Scheme 1: Connect to PNP-type PLC Input (Sourcing Input, COM tied to 0 V)

Brown 1 → +24 V
Blue 3 → 0 V
Black 4 → PLC input terminal I
PLC input COM terminal connected to 0 V

When cylinder magnet-ring triggers, internal reed closes; terminal I receives +24 V; input turns ON.

Scheme 2: Connect to NPN-type PLC Input (Sinking Input, COM tied to +24 V)

Brown 1 → +24 V
Blue 3 → 0 V
Black 4 → PLC input terminal I
PLC input COM terminal connected to +24 V

When cylinder magnet-ring triggers, reed closes; terminal I is pulled to 0 V; input turns ON.

⚠️Critical Engineering Reminders

Never directly drive inductive solenoid-valve coils. Fit free-wheeling diodes across coils, otherwise reed contacts will rapidly burn.
No reverse-polarity protection; swapping brown / blue wires will destroy sensor.
Max. allowable current: 500 mA direct wiring; limited to 80 mA when mounted via mounting accessories.
Reed-Switch Specific Troubleshooting
LED OFF: Supply fault; sensor misaligned relative to piston magnet-ring; cylinder without built-in magnet ring.
LED ON but no PLC input:

Incorrect PLC COM-common wiring;

Reed-contact burnout caused by inductive-load stress;

Loose M8-connector / cable connection.

Signal chattering: Loose T-slot mounting screw; demagnetized piston magnet-ring; nearby strong magnetic-field interference; reed-switch hysteresis (trigger-point offset on forward / reverse travel).
Quick Selection Summary

Quick-disconnect plug-in requirement: select -M8D variant (543861), match with NEBU extension cables.

Direct internal-machine hard-wiring: select -OE open-end bare-wire variant.

High-speed / millions-cycle continuous operation: discard SME reed-type; adopt SMT-8M Hall-effect series.

HS-code:8543709990