M12 5-Pin (A-Coded) Wiring Diagram for Machine Vision Lighting
Standard M12 5-pin A-coded pinout for industrial machine vision lighting: click a pin below — or a row in the table — to see its exact role, wire color, and the wiring mistakes automation engineers make most often.
Hover or click a pin — or a table row — to see its exact role and wiring pitfalls.
| Pin | Wire | Signal |
|---|---|---|
| 1 | Brown | +24 VDC |
| 2 | White | Dimming (0-10V / PWM) |
| 3 | Blue | 0V / GND |
| 4 | Black | Trigger / Strobe |
| 5 | Gray | FE (Functional Earth) |
PNP vs NPN & Strobe Mode
Most industrial vision cameras — including Cognex In-Sight, Keyence CV-X/XG, and Basler ace — drive their I/O trigger lines through optocoupled outputs rather than a direct transistor switch. This optical isolation protects the camera's internal electronics from voltage spikes on the lighting side, but it also means the trigger signal on Pin 4 must match the wiring convention the camera's output expects.
In a PNP (sourcing) configuration, the camera output switches Pin 4 to +24V to trigger the light — the strobe is active-high. In an NPN (sinking) configuration, the same output instead pulls Pin 4 down to 0V to trigger — the strobe is active-low. Wiring the wrong polarity won't damage the light, but the strobe will fire constantly (or never) — mismatched polarity is the single most common reason a "dead" light turns out to be perfectly functional hardware, simply wired backwards.
Overdrive warning
When a light is configured for pure Flash/Strobe (overdrive) operation, its LEDs are only rated to handle overdrive current during the strobe's short duty cycle — typically a few percent of the cycle time. Never leave Pin 4 held continuously high (or low, in NPN wiring) in this mode: without the trigger toggling, the driver keeps pushing overdrive current through the LEDs well past their thermal limit, and they will burn out — usually within seconds, not minutes.
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