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What Are the Color Coding Standards for Machine Vision Cables?

Connecting machine vision cameras, lights, controllers, and other components can feel like deciphering a rainbow if you don’t know the color codes. Unlike mains power where codes are strictly defined (e.g., brown/blue/green-yellow), ​machine vision cable color coding isn’t governed by a single, universal ISO or electrical standard. Instead, common practices and conventions have emerged within the industrial automation and imaging industries to promote consistency, reduce errors, and speed up installations.

Here’s a breakdown of the most common color coding conventions you’ll encounter:

1. ​M12 Connectors (Most Common for GigE Vision, USB3 Vision):
   • ​Sensor/Actuator (A-Coded): This widespread standard uses ​Green/Yellow colors for the key pins carrying power and signals.
     • Pin 1: Brown (typically +V power)
     • Pin 2: White (typically data +)
     • Pin 3: Blue (typically data -)
     • Pin 4: Black (typically 0V / Ground)
   • ​D-Coded (Ethernet / Gigabit): Becoming the dominant connector for high-speed GigE Vision cameras. Uses ​Blue connectors and often blue cable strain reliefs/boots.
     • Pin 1: White/Orange (TX+)
     • Pin 2: White/Green (RX+)
     • Pin 3: White/Blue (TX-)
     • Pin 4: White/Brown (RX-)
     • Pins 5-8: Solid Orange, Green, Blue, Brown (used in 8-wire PoE+ implementations)
   • ​X-Coded: Designed for 10 Gigabit Ethernet speeds, featuring ​Olive Green connectors. Less common currently but rising for very high-bandwidth vision.
     • Specific wire colors vary by manufacturer but follow twisted pair conventions internally.
2. ​Coax/SDI Cables:
   • ​Mini Coax (e.g., for analog cameras): Often identified by ​Yellow cable jackets and/or strain reliefs/boots.

• ​HD-SDI/3G-SDI: Frequently uses ​Black connectors or boots.

3. ​PowerFly / Power Connectors (e.g., M12 L-Coded, 5-pin M12 A-Coded):
   • Dedicated power cables often feature ​Olive Green or Gray connectors/strain reliefs/boots.
   • Common 4-pin power wiring (e.g., for lights):
     • Pin 1: Brown (+V)
     • Pin 2: Black (0V/GND)
     • Pin 3: White (Control/Input+)
     • Pin 4: Blue (Control/Input- or NC)
4. ​FireWire (IEEE 1394a/1394b – Legacy, but still present):
   • Traditionally associated with ​Red connectors or boots.

Important Caveats:

• ​The Primary Rule: Color Indicates Connector TYPE, NOT Wire Function. The key takeaway is that color (usually on the connector housing, boot, strain relief, or cable jacket) tells you what kind of connection it is:
  • ​Blue? Very likely D-Coded Ethernet/GigE Vision.
  • ​Green/Yellow pins? Very likely 4-pin M12 A-Coded (Sensors/Devices).
  • ​Yellow? Often analog coax.
  • ​Olive Green/Gray? Often dedicated power (PowerFly, etc.).
  • ​Red? Traditionally FireWire.
  • ​Black? Often HD-SDI.
• ​Wire Colors Inside: While conventions like green/yellow for A-coded pins exist, the actual internal wire insulation colors can still vary significantly between manufacturers within the connector shell. ​Never rely solely on inner wire colors for function!
• ​Function Follows Connector: Once you know the connector type via its color, the function (power, GigE, analog video) is defined by that connector type’s wiring standard. For example, plugging a blue (D-Coded) plug into a GigE port is correct.
• ​Exceptions Exist: Especially with generic cables, older installations, or very specialized components, colors might not match these conventions perfectly.
• ​Standard Trumps Color: Communication protocols (GigE Vision, USB3 Vision, Camera Link) define the electrical and functional requirements, not the physical color coding. Colors are a practical aid.
• ​PoE Compatibility: PoE (Power over Ethernet) requires specific wiring pairs (typically using the spare pairs in a D-Coded connection). PoE injectors/switches and compatible cameras handle this automatically, but the D-Coded connector color remains blue.

Common Applications & Color Summary:

Always Check!

While these color conventions are widely adopted to prevent misconnections (you wouldn’t plug a yellow coax into a blue GigE port!), ​ALWAYS verify the connector’s coding letter (A, B, D, X, L) molded onto the connector itself and consult the specific cable and equipment documentation for wiring details and pinouts. Using connector color as your first visual guide will dramatically reduce connection errors in your vision system setup.