CAN / serial gateways — Overview

A CAN / serial gateway is the small box that puts equipment speaking a serial protocol onto the boat's MUXEN CAN bus.

The boat's screens read one bus: the MUXEN CAN bus. A Victron charger talking VE.Direct, an air-conditioning unit answering Modbus RTU, each speak their own language on their own pair of wires. This box sits between the two, with one CAN connector on one side and four serial channels on the other, and translates continuously — in both directions where the equipment allows it. Once it is installed and configured, the third-party equipment shows up in the boat's interface next to native MUXEN devices, with no indication that it came from somewhere else.

Four channels means four pieces of equipment on one box. Each channel is independent: it carries its own device, with its own instance number, and one channel going quiet does not affect the other three.

Not every application only watches. Some command what they are connected to — a set point written into an air-conditioning unit, a charger told to change its mode. The application's own manual says which, and it matters before you wire anything.

One box, one job. The box does what the firmware loaded into it says it does. That firmware carries a product ID — the nine-digit number that names the finished product in the MUXEN catalogue — and the boat's Brain uses it to know which firmware belongs in which box. Loading a different application's firmware turns a Frigomar gateway into a VE.Direct gateway; the product ID is how you tell them apart.

Every box, whatever its application, is also a small generic I/O device: one relay output and one analog input, usable for anything the installation needs — a relay driving a valve, a tank sender.

The catalogue

Product ID	Application	What it connects	Serial/Modbus	Serial/Modbus V2
010010002	VE.Direct	up to four Victron devices on VE.Direct — batteries, chargers, inverters, MPPT solar regulators	✔	✔
010010019	Frigomar	up to four Frigomar air-conditioning units on Modbus RTU	✔	✔
010010028	Blue Airco	up to four Blue Airco air-conditioning units on Modbus RTU	✔	✔

"Serial/Modbus" and "Serial/Modbus V2" are the two hardware generations currently built — see The hardware. A ✔ means a signed firmware is built and published for that combination.

Each application has its own manual — follow its name in the table above. Start there for wiring, supported equipment models and commissioning. What you are reading covers what is true of every box in the line, whatever firmware it carries.

What is common to all of them

• The MUXEN side. Always one CAN port, always 500 kbit/s, always the same addressing: a function (what kind of device this is) and an instance (which one of them). See Reference.
• The equipment side. Always four serial channels, numbered 1 to 4. Their electrical mode and their speed are fixed by the firmware — no jumper, no DIP switch, nothing to set on the board. See The hardware.
• Configuration. No screen, no buttons, no web page. Every setting is read and written over the CAN bus from the Brain, with muxen-uds. A factory-fresh box answers on the bus but publishes nothing until it has been given an instance number.
• Firmware updates. Over the same bus, without opening the box — see Loading and updating a firmware. A failed update cannot brick a box: the firmware it was already running is never touched until a complete, correctly signed image has arrived.
• Faults are forwarded. A fault reported by the equipment on a channel is republished as a MUXEN diagnostic code against the device that channel carries, so it turns up in the boat's alarm list rather than staying hidden inside the box.
• One LED. The single system LED is the whole local diagnostic. It tells you whether the application is running or not — see Common mistakes.

Where to go next

I want to…	Read
know what to order and how to wire it	The hardware
load or update a firmware	Loading and updating a firmware
understand why it is not working	Common mistakes
look up an ID, a function code, a LED code	Reference
commission one specific application	its own manual — see the catalogue