@modbus-ts/protocol

Modbus frame encoder/decoder for TCP, RTU, and ASCII.

Installation

pnpm add @modbus-ts/protocol

Core Exports

• ModbusWireMode
• encodeReadHoldingRegisters / encodeReadHoldingRegistersByMode
• encodeWriteSingleRegister / encodeWriteSingleRegisterByMode
• encodeWriteMultipleRegisters / encodeWriteMultipleRegistersByMode
• decodeResponse / decodeResponseByMode

Minimal Example

import { decodeResponseByMode, encodeReadHoldingRegistersByMode } from '@modbus-ts/protocol'

const request = encodeReadHoldingRegistersByMode({
  mode: 'rtu',
  transactionId: 1,
  unitId: 1,
  startAddress: 0,
  quantity: 2,
})

const response = decodeResponseByMode(new Uint8Array([1, 3, 4, 0, 1, 0, 2, 42, 57]), 'rtu')

Supported Function Codes

• FC1 Read Coils
• FC2 Read Discrete Inputs
• FC3 Read Holding Registers
• FC4 Read Input Registers
• FC5 Write Single Coil
• FC6 Write Single Register
• FC15 Write Multiple Coils
• FC16 Write Multiple Registers

Point Mapping

| Function Code | Data Type | Read/Write | Typical API in client | | ------------- | ------------------ | ---------- | ---------------------- | | FC1 | Coils | Read | readCoils | | FC2 | Discrete Inputs | Read | readDiscreteInputs | | FC3 | Holding Registers | Read | readHoldingRegisters | | FC4 | Input Registers | Read | readInputRegisters | | FC5 | Single Coil | Write | writeSingleCoil | | FC6 | Single Register | Write | writeSingleRegister | | FC15 | Multiple Coils | Write | writeMultipleCoils | | FC16 | Multiple Registers | Write | writeMultipleRegisters |

Packages

• high-level Modbus client
• shared contracts, types, and errors
• FC1/FC2/FC3/FC4/FC5/FC6/FC15/FC16 frame encode/decode for TCP/RTU/ASCII
• serial request queue with priority
• polling engine and range merge
• Node TCP transport with reconnect
• Node UDP transport
• browser WebSocket transport with reconnect
• typed Electron main/renderer bridge
• Electron IPC transport adapter
• WebSocket to TCP binary relay gateway
• register-value codec helpers
• shared async and comparison utilities