Nucleo GX Manual

The following table lists the required ComAp Modbus configuration. In addition to the listed holding registers, Coil 4700 is used to start and stop the genset.

The following table lists the Modbus holding registers the GX device reads. Note that this Modbus table reflects the DSE register list, not the GX device's. These definitions follow the Deep Sea Electronics GenComm standard (Version 2.236 MF). The Modbus register list for reading this data from the GX device can be found in the download section on the Victron website.

The registers marked required in the Remarks column are critical for identifying the DSE genset controllers in the GX device and for proper operation of the Victron ecosystem with the generator. Don't change them. All other registers are optional.

Note: Page and Register offset are terminology from the DSE GenComm standard.

Terms and abbreviations used throughout the GX Manual, collected here for quick reference. Where a term has a specific meaning in the Victron ecosystem, that meaning is given rather than a generic definition.

fffffff

AC (Alternating Current)

Power that periodically reverses direction, the type supplied by the grid, a generator, or a shore power connection.

Assistant

A small program loaded into a Multi or Quattro through VEConfigure to add specific behavior, such as the ESS Assistant that enables ESS mode, or a current-sensor assistant that reads an external current transformer. Not to be confused with Home Assistant, an unrelated third-party home-automation platform mentioned once in the manual.

BatteryLife

An ESS charge and discharge algorithm, selected as the "Optimized with BatteryLife" mode, that manages a dynamic minimum SoC limit to protect the battery, prioritizing a full recharge during periods of poor solar yield. Its status is reported as one of three states: Self-Consumption, Sustain, or Recharge.

BLE (Bluetooth Low Energy)

The Bluetooth standard used by the GX device and by supported sensors (Mopeka, Ruuvi, Gobius, and others) for short-range wireless connections that draw little power.

BMS (Battery Management System)

The electronics inside or attached to a battery that monitor its condition and, in managed systems, communicate charge and discharge limits (see CVL, CCL, DCL) to the GX device over CAN bus.

BMV

Victron's range of battery monitors. A BMV connected via VE.Direct or VE.Can can act as the SoC (State of Charge) source for the system.

CAN bus

A robust two-wire communication bus used for VE.Can, NMEA 2000, and RV-C. Multiple devices share the same pair of wires and exchange short data messages.

CCGX (Color Control GX)

The GX device model that the Ekrano GX succeeds.

CCL (Charge Current Limit)

The maximum charge current a battery will accept, reported by a managed BMS battery so that connected chargers do not exceed it.

CVL (Charge Voltage Limit)

The maximum charge voltage a battery will accept, reported by a managed BMS battery and followed by connected inverter/chargers and solar chargers when DVCC is active.

DCL (Discharge Current Limit)

The maximum current a managed BMS battery allows to be drawn from it, used by DVCC-capable systems to protect the battery.

DGN (Data Group Number)

The RV-C equivalent of a PGN, a numeric identifier that tells devices on an RV-C network what kind of data a message contains.

DHCP (Dynamic Host Configuration Protocol)

The mechanism most routers use to automatically hand out an IP address to the GX device on a network, as opposed to entering one manually.

Digital input

A physical input on the GX device that reads a simple on or off signal, used for example to detect a bilge pump running, a door switch, or a generator status signal.

DVCC (Distributed Voltage and Current Control)

A GX device setting (Settings, System Setup, Charge Control) that turns the GX device from a passive monitor into an active controller, coordinating charge voltage and current across all connected chargers and the battery.

EEBUS

A European smart-grid communication standard supported by the GX device for interacting with compatible energy devices such as heat pumps.

EGX

Short form for the Ekrano GX.

ESS (Energy Storage System)

A Victron system design for grid-connected installations that requires a Multi or Quattro inverter/charger, a GX device, and a battery, most often paired with solar. It stores solar energy for later use, keeps supplying power during a grid outage, and can automatically import from or export to the grid depending on how it's configured and what local grid rules allow.

EVCS (EV Charging Station)

A Victron electric vehicle charging station that can be monitored and, depending on configuration, controlled by the GX device.

GPS

Used by the GX device (via USB GPS or NMEA 2000 GPS) to provide position and time data, relevant mainly for marine and mobile installations.

GX device

The general term for any Victron communication centre running Venus OS, including the Ekrano GX, Cerbo GX, Cerbo S GX, and Venus GX.

IO Extender

Short for the GX IO-Extender 150, a USB-connected accessory that adds extra relay, digital input, and PWM outputs to a GX device.

IP rating (Ingress Protection rating)

A two-digit code (for example IP43, IP54, IP65) describing how well a device is sealed against dust and water. Higher numbers mean better protection; the manual quotes different ratings for the front and back of the GX housing.

J1939

The underlying CAN bus standard, defined by SAE, that both NMEA 2000 and RV-C are built on top of.

LAN (Local Area Network)

A wired or WiFi network confined to one site, used to reach the GX device's Remote Console without going through the internet.

LTE (Long-Term Evolution)

The technical name for the 4G mobile-data standard. The optional GX LTE 4G accessory, which also falls back to 3G or 2G where 4G coverage isn't available, gives a GX device its own cellular internet connection. It only connects the GX device itself; it does not share that connection with laptops, phones, or other devices.

MFD (Multi-Function Display)

A marine chartplotter or multi-function display, from brands such as Raymarine, Navico, Garmin, or Furuno, that can show Victron system data through either a brand-specific app integration or directly over NMEA 2000.

MK3-USB

A Victron interface used to link a secondary VE.Bus system to a GX device. Systems connected this way are not controlled by DVCC by default.

Modbus TCP

An industrial communication protocol the GX device can expose over the network, used by third-party monitoring or automation systems, and specifically by digital inputs and generator-controller integrations described in the manual.

MPPT (Maximum Power Point Tracking)

Victron's range of solar charge controllers, which optimise the power drawn from a solar array. Connects to the GX device by VE.Direct or VE.Can.

MQTT

A lightweight messaging protocol the GX device can publish data to, used for custom integrations such as home automation or Node-RED.

Multi / Quattro

Shorthand for Victron's MultiPlus and Quattro inverter/chargers, the devices most commonly connected to a GX device over VE.Bus.

NMEA 2000

A marine CAN bus standard (built on J1939) that lets navigation electronics, sensors, and the GX device share data such as tank levels, battery status, and GPS position with a chartplotter or multi-function display.

NO / NC (Normally Open / Normally Closed)

Relay contact states used for the GX device's built-in relays and other relay-controlled wiring, such as generator start and stop signals. Normally Open means the contact stays open until triggered; Normally Closed is the reverse.

Node-RED

A visual programming tool that can run on the GX device to build custom automations and virtual switches beyond what the standard menus offer.

Opportunity Loads

A GX device feature that automatically routes surplus solar power to flexible AC loads (for example an EV charger or water heater) once the battery is sufficiently charged.

PGN (Parameter Group Number)

The NMEA 2000 identifier that tells devices what kind of data a message contains, similar to a message-type number.

Remote Console

The user interface for a GX device, opened over the local network, through the built-in WiFi Access Point, or through VRM.

RGBW / CCT

Lighting output types the GX device can control: RGBW mixes red, green, blue, and white channels for colour lighting, while CCT (Correlated Colour Temperature) adjusts a light between warm and cool white.

RS485

A wired serial communication standard used by some generator controllers (DSE, ComAp, ClearView) and other third-party equipment to connect to a GX device.

RV-C (Recreational Vehicle Controller Area Network)

A CAN bus based protocol, similar in purpose to NMEA 2000, used mainly in North America so RV appliances and control panels can communicate.

SCS (Shared Current Sense)

A DVCC feature where the GX device forwards a measured battery current reading to connected chargers so they do not need their own current sensor.

SoC (State of Charge)

The remaining charge in a battery, shown as a percentage.

STS (Shared Temperature Sense)

A DVCC feature where the GX device forwards a measured battery temperature to connected chargers so they can adjust charging accordingly.

SVS (Shared Voltage Sense)

A DVCC feature, enabled by default, where the GX device selects the most accurate available battery voltage reading and shares it with connected chargers.

TCP / UDP

The two basic ways devices exchange data over a network.

USB

Used on the GX device for firmware updates from a USB stick, for connecting the IO Extender and other Victron USB devices, and for some third-party accessories.

VE.Bus

Victron's proprietary communication bus, mainly used to connect one or more MultiPlus or Quattro inverter/chargers to a GX device.

VE.Can

Victron's implementation of a CAN bus port, used to connect Victron CAN bus devices, or, alternatively, to run NMEA 2000 or RV-C on the same physical port.

VE.Direct

Victron's point-to-point communication port (cable or Bluetooth) used by single devices such as a BMV, an MPPT, an Orion XS, or a Smart IP43 Charger.

Venus OS

The operating system that runs on every GX device.

VRM (Victron Remote Management)

Victron's free cloud portal for monitoring, remote configuration, alarms, and remote firmware updates. Requires the GX device to have an internet connection.

WiFi Access Point

A mode where the GX device creates its own WiFi network so a phone or laptop can connect directly to it without an existing router, useful for first-time setup.