Keybox: add keypad-controlled outputs to any vehicle or boat
You have a CAN keypad, or you’re about to specify one. The buttons are the easy part. The real question is what sits between the keypad and the loads — the lights, pumps, motors and actuators the operator wants to switch. On a vehicle or boat with a full digital switching system, that controller already exists. On everything else, it doesn’t. That gap is what the Keybox fills.
What is a CAN bus relay module, and when you need one
A CAN bus relay module is a device that receives commands over the CAN bus and drives physical electrical loads through relays and solid-state outputs. Instead of running a wire from every switch to every load, the keypad and the relay module talk over a two-wire CAN bus, and the module does the switching close to the loads.
You need one whenever there is no controller in the system already capable of driving outputs. A keypad on its own is an input device: it sends messages, it doesn’t carry current. If the vehicle or boat has no VCU, PLC or dedicated switching controller listening on the bus, those keypad messages have nowhere to go. A CAN bus relay module is the missing output stage — the component that turns a button press into current on a circuit.
This is a common situation in off-highway vehicles, specialty vehicles and boats built in small series, where the cost and complexity of a full digital switching architecture aren’t justified but the builder still wants clean, configurable keypad control.
How the Keybox works
The Keybox is Blink Marine’s CANbus I/O relay module (commercially Keybox3) for 12V and 24V systems. It provides thirteen fused circuits — 2 MOSFET outputs and 11 relay outputs — each protected against overcurrent, with an indicator LED that blinks when a fuse has blown, so faults are visible without a meter.
Watch how the Keybox works:
A few characteristics matter when specifying it:
- Configurable circuits. Each circuit can be set as a power output or a digital input — or both at once — with level- or edge-triggered logic. An input can be linked to multiple outputs. Configuration is done in software, not in the wiring.
- PWM outputs. Circuits can be driven with PWM for dimming lights or setting throttle-style positions, rather than simple on/off.
- Daisy-chain. Multiple Keyboxes and one or more Blink keypads share a single bus, which substantially reduces wiring.
The Keybox speaks CAN (CANopen / J1939) and RS485, is rated IP67 and IP69K across -40 °C to +85 °C, and carries UN ECE R10 rev.02 EMC type-approval (E24*10R06/02*5519*00) — relevant wherever road-vehicle electromagnetic compatibility has to be documented.
Two ways to use a Keybox
The same module covers two distinct roles.
1. As a standalone keypad system (the main use)
Paired with a Blink Marine keypad from the PowerKey or PowerKey Pro (PKP) series, the Keybox becomes a complete, self-contained switching system. The operator presses a button; the keypad sends the message; the Keybox drives the circuit. No third-party controller, no custom software stack.
This is where the Keybox does most of its work, and where its configurability lives. Everything is set up in KCS (Keybox Configuration Software), a user-accessible tool that doesn’t require factory involvement; it connects to a PC over an RS485-USB or CAN-USB adapter, and firmware is field-updatable. In KCS you add the keypad models — up to 11 keypads on the bus, each with a unique address — and map every button to a circuit and a behaviour: momentary, toggle, multi-step sequences, dimmer, countdown, bilge-pump auto/manual, and more. What each button does, which circuit it drives, how the LED responds — all of it lives in the configuration, not the harness.
Typical loads are what you’d expect on a working vehicle or boat: lights, electric motors, bilge pumps, mechanical arms.
2. As a CAN slave, to expand an existing system
The Keybox can also be set up as a CAN slave: an output node commanded by a controller that is already in place. This is useful when an existing system is effectively “full” — you need a few more switched circuits but don’t want to redesign the architecture to get them. The Keybox adds those outputs on the bus, driven by the host controller, without touching the rest of the system.
It’s worth being precise about where the Keybox’s job ends. Blink Marine builds the keypad and the relay module and stands behind their behaviour on the bus: the protocol they implement, the outputs they drive, the configuration options they expose. How that CAN-conformant building block is wired into a wider machine architecture is the integrator’s domain. The delivery point is a standards-compliant module that does what its configuration says.
Specs and variants
The Keybox ships in four variants, so the current rating matches the loads:
| Model | Voltage | MOSFET | Relays |
|---|---|---|---|
| KB312V-10A | 12V | 2×3A | 11×10A |
| KB312V-05A | 12V | 2×3A | 11×5A |
| KB324V-05A | 24V | 2×3A | 11×5A |
| KB312V-05-10A | 12V | 2×3A | mixed |
Shared across all of them: 13 fused circuits, PWM-capable outputs, CANopen/J1939 and RS485, IP67/IP69K, -40 °C to +85 °C, daisy-chain support and KCS configuration.
Specifying the Keybox
If you’re building a vehicle or a boat that needs configurable keypad control but doesn’t warrant a full digital switching system, the Keybox is the shortest path from button to load: thirteen circuits, configured in software, on the same bus as the keypad. A separate scenario is expansion: when your vehicle or boat already has an on-board control system, the Keybox can instead act as a CAN slave to add outputs to it.
See the full specifications on the Keybox product page, or order it on the Blink Marine shop.