基于纯JavaScript实现的MODBUS-RTU（串口和TCP） modbus-serial

modbus-serial

如果你需要使用JavaScript来操作一台RS458的设备，那么你一定不能错过这个库 modbus-serial。

安装和使用

npm install modbus-serial

支持的功能码

功能码	函数
FC1 读取读线圈寄存器	`readCoils(coil, len)`
FC2 读离散输入寄存器	`readDiscreteInputs(addr, arg)`
FC3 读保持寄存器	`readHoldingRegisters(addr, len)`
FC4 读输入寄存器	`readInputRegisters(addr, len)`
FC5 写单个线圈寄存器	`writeCoil(coil, binary)`
FC6 写单个保持寄存器	`writeRegister(addr, value)`
FC15 写多个线圈寄存器	`writeCoils(addr, valueAry)`
FC16 写多个保持寄存器	`writeRegisters(addr, valueAry)`
FC43/14 读保持寄存器	`readDeviceIdentification(id, obj)`

客户端串行：

modbus-RTU (SerialPort)：通过串行线路，需要node serialport。
modbus-RTU (RTUBufferedPort)：通过缓冲串行线路，需要node serialport。
modbus-ASCII (AsciiPort)：通过串行线路，需要node serialport。

客户端TCP：

modbus-TCP (TcpPort)：通过TCP/IP线路。
modbus-RTU (UdpPort)：通过C701服务器，商业UDP到串行桥。
modbus-RTU (TcpRTUBufferedPort)：通过TCP/IP线路，TCP/IP串行RTU缓冲设备。
modbus-RTU (TelnetPort)：通过Telnet服务器，TCP/IP串行桥。

服务器

modbus-TCP (ServerTCP)：通过TCP/IP线路。

示例

读取和写入

// create an empty modbus client
const ModbusRTU = require("modbus-serial");
const client = new ModbusRTU();// open connection to a serial port
client.connectRTUBuffered("/dev/ttyUSB0", { baudRate: 9600 }, write);function write() {client.setID(1);// write the values 0, 0xffff to registers starting at address 5// on device number 1.client.writeRegisters(5, [0 , 0xffff]).then(read);
}function read() {// read the 2 registers starting at address 5// on device number 1.client.readHoldingRegisters(5, 2).then(console.log);
}

读取多个从站

const ModbusRTU = require("modbus-serial");
// create an empty modbus client
const client = new ModbusRTU();
// open connection to a serial port
client.connectRTUBuffered("/dev/ttyS0", { baudRate: 9600 });
// set timeout, if slave did not reply back
client.setTimeout(500);// list of meter's id
const metersIdList = [10, 11, 12, 13, 14];const getMetersValue = async (meters) => {try{// get value of all metersfor(let meter of meters) {// output value to consoleconsole.log(await getMeterValue(meter));// wait 100ms before get another deviceawait sleep(100);}} catch(e){// if error, handle them here (it should not)console.log(e)} finally {// after get all data from slave, repeat it againsetImmediate(() => {getMetersValue(metersIdList);})}
}const getMeterValue = async (id) => {try {// set ID of slaveawait client.setID(id);// read the 1 registers starting at address 0 (first register)let val =  await client.readInputRegisters(0, 1);// return the valuereturn val.data[0];} catch(e){// if error return -1return -1}
}const sleep = (ms) => new Promise(resolve => setTimeout(resolve, ms));// start get value
getMetersValue(metersIdList);

ModbusTCP 服务

// create an empty modbus client
const ModbusRTU = require("modbus-serial");
const vector = {getInputRegister: function(addr, unitID) {// Synchronous handlingreturn addr;},getHoldingRegister: function(addr, unitID, callback) {// Asynchronous handling (with callback)setTimeout(function() {// callback = function(err, value)callback(null, addr + 8000);}, 10);},getCoil: function(addr, unitID) {// Asynchronous handling (with Promises, async/await supported)return new Promise(function(resolve) {setTimeout(function() {resolve((addr % 2) === 0);}, 10);});},setRegister: function(addr, value, unitID) {// Asynchronous handling supported also hereconsole.log("set register", addr, value, unitID);return;},setCoil: function(addr, value, unitID) {// Asynchronous handling supported also hereconsole.log("set coil", addr, value, unitID);return;},readDeviceIdentification: function(addr) {return {0x00: "MyVendorName",0x01: "MyProductCode",0x02: "MyMajorMinorRevision",0x05: "MyModelName",0x97: "MyExtendedObject1",0xAB: "MyExtendedObject2"};}
};// set the server to answer for modbus requests
console.log("ModbusTCP listening on modbus://0.0.0.0:8502");
const serverTCP = new ModbusRTU.ServerTCP(vector, { host: "0.0.0.0", port: 8502, debug: true, unitID: 1 });serverTCP.on("socketError", function(err){// Handle socket error if needed, can be ignoredconsole.error(err);
});