The M8 Connector: Compact Industrial Connectivity
The M8 circular connector is the compact sibling to the M12 — defined under IEC 61076-2-104 with an 8 mm threaded coupling. Where space and weight matter (miniature sensors, valve manifolds, mobile robotics, IO-Link slave devices), the M8 delivers a robust IP67-rated connection in less than half the footprint of a comparable M12. Katlax manufactures the full M8 portfolio at our Santej, Gandhinagar facility — A-coded, B-coded, and D-coded variants across 3 / 4 / 5 / 6 / 8 pin configurations, all TUV Rheinland EN/IEC certified.
M8 is the default choice for sensor-side connections in space-constrained machinery: inductive proximity sensors, photoelectric switches, miniature limit switches, valve solenoids, encoder feedback on small servos. When an M12 won't fit on the sensor body and a hardwired pigtail isn't reusable, M8 closes the gap.
M8 Coding Variants — A, B, D
M8 inherits the coding-key concept from its larger M12 sibling — a small mechanical feature inside the housing that prevents a signal cable from mating with an Ethernet socket (or vice-versa). M8 supports three codings, each mapped to a specific signal class:
| Coding | Pins | Primary use case | Notes |
|---|---|---|---|
| A-Coded | 3 / 4 / 6 / 8 | Sensors, actuators, low-voltage signal | The standard M8. Default for proximity, photoelectric, magnetic switches. 4-pin is the most widely deployed configuration. |
| B-Coded | 5 | Fieldbus (small-format) | Reverse-keyed from A for fieldbus and IO-Link applications where keying must prevent miswiring. |
| D-Coded | 4 | Industrial Ethernet (Cat-5e, 100 Mbit) | Shielded 4-pin Ethernet in the compact M8 form factor. Common on small Industrial-Ethernet sensors, IO-Link masters, AGV boards. |
For higher-pin or higher-current applications, use the M12 family. M8 caps out around 4 A per pin and ~60 V — beyond that you need the larger thread. Full wire-colour reference for every M8 coding lives on the Pin Assignment & Wire Colour Code page.
Pin Configurations and Wire-Colour Codes
Standard IEC 60757 wire colours for the most common A-coded M8 variants:
| Pin | 3-Pin (A) | 4-Pin (A) | 6-Pin (A) | 8-Pin (A) |
|---|---|---|---|---|
| 1 | BN (Brown) | BN (Brown) | BN (Brown) | WH (White) |
| 2 | — | WH (White) | WH (White) | BN (Brown) |
| 3 | BU (Blue) | BU (Blue) | BU (Blue) | GN (Green) |
| 4 | BK (Black) | BK (Black) | BK (Black) | YE (Yellow) |
| 5 | — | — | GY (Grey) | GY (Grey) |
| 6 | — | — | PK (Pink) | PK (Pink) |
| 7 | — | — | — | BU (Blue) |
| 8 | — | — | — | RD (Red) |
M8 B-coded 5-pin and D-coded 4-pin follow distinct sequences — the complete reference has the tables and face-view diagrams per coding.
Technical Specifications
- Standard: IEC 61076-2-104 (signal / data), IEC 61076-2-114 references for higher-current variants.
- IP rating: IP67 standard when mated (immersion to 1 m / 30 min per IEC 60529); cap unmated ports with IP67 dust caps.
- Current rating: Up to 4 A per contact (varies by coding and contact area).
- Voltage: 60 V AC/DC standard for signal/data variants.
- Mating cycles: 100 minimum per IEC 61076-2-104; field-tested to 500+ in industrial environments.
- Operating temperature: −25 °C to +85 °C standard; extended ranges available with TPE jacket.
- Vibration / shock: Per IEC 60068-2-6 (10–55 Hz, 1.5 mm) and IEC 60068-2-27 (50 G, 11 ms half-sine).
Cable Material — PVC, PUR, or TPE?
- PVC — general-purpose, cost-optimised. Suitable for static installations in dry, room-temperature environments. Not recommended for continuous flex.
- PUR (polyurethane) — abrasion-resistant, oil-resistant, suitable for drag-chain and high-flex applications (machine tools, robotics, AGVs). 5–10× the flex life of PVC.
- TPE (thermoplastic elastomer) — chemical-resistant, food-safe options available. Used in food processing, pharma, washdown environments.
Datasheets for every cable jacket option live in the downloads section.
How to Select the Right M8 Connector
- What's the signal? Sensor (A-coded), fieldbus (B-coded), Industrial Ethernet (D-coded).
- How many pins? Most sensors are 3 or 4-pin. Count signals + power.
- Male or female? Convention: the device-side connector is female; the cable-side connector is male.
- Cable length? Standard 2 m, 5 m, 10 m off-the-shelf; custom to 30 m on a single pre-terminated SKU.
- Cable jacket? PVC for static, PUR for flex, TPE for chemical/food-safe.
- Termination? Pre-molded (factory IP67 seal — recommended for new builds) or field-attachable.
Stuck between configurations? Send your application requirements and our engineering team will quote within 24 business hours.
Applications
- Factory automation: Inductive proximity sensors, photoelectric switches, miniature limit switches, IO-Link slave devices. 4-pin A-coded dominates.
- Valve and actuator banks: Direct-connect valve manifolds where M12 won't fit on the valve body.
- Mobile robotics / AGVs: Compact, vibration-immune connections on AGV navigation sensors and motor feedback.
- Encoders: Small servo motor encoder feedback (M8 4-pin or 5-pin).
- Industrial Ethernet edge devices: M8 D-coded for small IIoT sensors, Industrial-Ethernet-enabled measurement modules.
- Building automation: Compact HVAC sensors, occupancy detectors, intelligent lighting where M12 is overkill.
Why Katlax for M8
With 30+ years of manufacturing experience and ISO 9001:2015 certification, Katlax supplies M8 connectors to 4,000+ customers across 35+ countries. Vertically integrated manufacturing means injection moulding, cable processing, over-moulding, and 100% electrical + IP-leak testing all happen under one roof in Gandhinagar.
Certifications: TUV Rheinland EN & IEC (M8 series, certificate R 60113557), CE, UL (Subject-764 traceability), UKCA, ISO 9001:2015, plus self-declaration on RoHS and REACH. All certificates downloadable from our downloads page.
Lead times: standard SKUs 1–2 weeks ex-works; custom cable assemblies 3–4 weeks; OEM private-label runs from 500 pieces with 8–12 week tooling.
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