CJD Plug Standard — GX16-4
This document defines the single connector standard for buildings (Domus): a GX16-4 (“aviation”) threaded connector. It is used on garage walls and service panels to deliver 24 V DC power and a simple status/ID signal to vehicles and devices.
Scope: buildings and fixed infrastructure only. Vehicle-side wiring is covered in the Robulus docs.
1) Electrical Specification
- System Voltage: 24 V DC (nominal), tolerance ±10%
- Maximum Current (continuous): 15 A (class limits may be lower)
- Connector Type: GX16-4 (4-pin)
- Ingress Protection: IP55+ when fully assembled (panel gasket + mated plug)
- Default State: Power OFF upstream until status/ID check passes
Recommended protections (upstream of the socket):
- eFuse/current-limit set to site rating (≤ 15 A)
- TVS diodes on power and signal lines (24 V system)
- Over-temperature/over-current cut-off
- Ground-fault protection per city electrical code
2) Mechanical Standard
- Panel Socket (female): GX16-4, panel-mount
- Mounting Location: Exterior garage/service wall, 40–60 cm above ground
- Thread Diameter: 16 mm (GX16 standard); panel cutout Ø16 mm
- Fixation: Threaded bushing + lock nut (supplied with socket)
- Key Notch Orientation: 12:00 (upwards) — enforce during installation
- Cable Entry (plug side): Strain relief clamp or PG gland
- Materials: Nickel-plated brass shell, dielectric insert, tin-plated contacts
Robotic integration: If a robot arm performs coupling, it must support a rotating grip with ≥ 1 N·m torque to screw/unscrew the coupling nut.
3) Pin Assignment
Pins are numbered clockwise when viewing the socket (female) face-on, with the key notch at 12:00.
| Pin # | Name | Direction | Description |
|---|---|---|---|
| 1 | +24V DC | Out | Positive power line |
| 2 | GND | – | Ground / negative |
| 3 | STATUS | I/O | Digital line for presence check or ID |
| 4 | RESV | – | Reserved (future use) |
STATUS line (baseline behavior):
- Logic level 3.3 V tolerant (accepts 3.3–5 V input from controller)
- Default pull-up in the building controller (10–47 kΩ)
- Presence detect = vehicle side pulls low on plug-in (open-drain recommended)
- Optional: 1-Wire™/UART-based ID in future revisions (keep pin free of heavy noise)
4) Cable & Wiring
Building side (panel → controller):
- Power pair: ≥ 2.5 mm² (AWG 14) copper for 15 A runs up to 10 m
- Signal pair: 0.22–0.5 mm² (AWG 24–20) twisted (optional), shield to GND at controller
- Insulation: ≥ 60 V rating, 105 °C preferred (silicone or XLPE)
- Keep power & signal separated where practical; avoid parallel runs with high-current AC
Vehicle/device side (plug):
- Use a molded or metal-shell GX16-4 plug (male) with strain relief
- Keep STATUS wiring away from ESC/PWM lines; add 100 Ω series + 100 nF to GND near MCU if noisy
5) Installation Procedure (Panel Socket)
- Cutout: Drill/cut Ø16 mm hole; deburr.
- Gasket: Fit IP gasket between socket flange and panel.
- Orient: Align key notch to 12:00.
- Fix: Insert socket, tighten lock nut (snug; do not deform panel).
- Wire: Crimp or solder pigtails; observe pin numbers (see table).
- Protect: Route to controller via gland/conduit; add eFuse/TVS upstream.
- Label: Apply pinout sticker within 10 cm of socket; mark circuit rating (e.g., “24 V DC / 15 A”).
- Test: Perform continuity and polarity checks before energizing.
6) Commissioning & Tests
- Continuity/Polarity: Verify Pin-1 = +24 V, Pin-2 = GND (with supply OFF first).
- STATUS check: Plug in a test dongle that pulls STATUS low → controller should arm relay/enable power.
- Load test: Apply 75% rated load for 10 min; ensure < 30 °C rise at contacts and no voltage sag > 10%.
- Ingress: Spray test at low pressure; inspect for moisture ingress.
- Disconnect safety: Power must drop within < 50 ms after unscrew/disconnect (controller rule).
7) Safety Notes
- Never exceed 15 A continuous on a single GX16-4 connector.
- Do not hot-plug under heavy load; controller must disable power until STATUS passes.
- Ensure proper strain relief; avoid sharp cable bends at the plug entry.
- Use only connectors with intact seals and undamaged threads.
8) Bill of Materials (reference)
- GX16-4 Panel Socket (female), IP-gasketed, nut included
- GX16-4 Cable Plug (male) with strain relief
- Panel IP gasket (NBR or silicone)
- eFuse/current limiter (programmable or fixed, ≤ 15 A)
- TVS diodes (24 V power line + signal line)
- Label “24 V DC / 15 A — CJD GX16-4” + pinout diagram
9) Marking
- Near each socket:
CJD GX16-4 | 24 V DC | Max 15 A | Pins: 1=+24V, 2=GND, 3=STATUS, 4=RESV - Optional QR linking to this spec.
10) Revision History
- v3.0 — Baseline GX16-4 standard; status line defined; IP55+ requirement; 12:00 notch orientation.