signalk-daly-bms

A SignalK plugin that reads data from a Daly Smart BMS via RS485 serial connection and publishes it to the SignalK data model.

Features

• Total voltage, current and state of charge (SOC)
• Individual cell voltages (4S, 8S, 16S — auto-detected)
• Battery temperature
• Fault/alarm flag
• Configurable serial port, poll interval and battery instance name
• Works with any USB-to-RS485 adapter

Hardware requirements

• Daly Smart BMS with RS485 port (all cell configurations supported)
• USB-to-RS485 adapter connected to the SignalK host (e.g. Raspberry Pi)
• RS485 cable wired to the BMS: connect A, B and GND

Wiring — Daly USB-RS485 cable

The Daly USB-RS485 cable has a 5-pin JST GH connector. With the contacts facing you, pin 1 is on the right (JST standard).

  contacts facing you, locking latch on top

  ┌─────────────────────────┐
  │  5    4    3    2    1  │
  │  TX   RX   GND  A    B  │
  └─────────────────────────┘
       ←————————————————————

| Pin | Colour | Signal | Connect to RS485 adapter | |-----|--------|--------|--------------------------| | 1 | White | B (RS485−) | B | | 2 | Green | A (RS485+) | A | | 3 | Black | GND | GND | | 4 | — | RX (UART) | not used | | 5 | — | TX (UART) | not used |

Note: if you get no response, swap A and B — some adapters label them in reverse.

Installation

From the SignalK app store

Search for signalk-daly-bms in the SignalK server app store and click Install.

Manual

cd ~/.signalk
npm install signalk-daly-bms

Restart the SignalK server after installation.

Configuration

Open the SignalK server web UI → Server → Plugin Config → Daly BMS (RS485).

| Setting | Default | Description | |---|---|---| | Serial port | /dev/ttyUSB0 | Serial device of the RS485 adapter | | Baud rate | 9600 | Must match BMS setting (9600 is standard) | | Poll interval | 5 | Seconds between data requests | | Battery instance | house | Instance name used in the SignalK path |

On Linux the port is typically /dev/ttyUSB0 or /dev/ttyUSB1.
On Windows use COM3, COM4 etc.

The pi user may need to be added to the dialout group for serial port access:

sudo usermod -a -G dialout pi

SignalK paths

All values are published under electrical.batteries.<instance>.*:

| Path | Unit | Description | |---|---|---| | electrical.batteries.house.voltage | V | Total pack voltage | | electrical.batteries.house.current | A | Current (negative = discharging) | | electrical.batteries.house.capacity.stateOfCharge | ratio | State of charge (0–1) | | electrical.batteries.house.temperature | K | Battery temperature | | electrical.batteries.house.cells.1.voltage | V | Cell 1 voltage | | electrical.batteries.house.cells.N.voltage | V | Cell N voltage (N = 1 … cell count) | | electrical.batteries.house.alarm | boolean | True if any fault flag is set |

Cell count is read automatically from the BMS on startup.

Compatibility

Tested on:

• Daly Smart BMS 4S 12V 500A

Should work with any Daly Smart BMS that supports the standard RS485 protocol (all cell counts).

License

MIT