modbus协议使用【android串口通信】

modbus协议使用【android串口通信】

本文的目的是android端与上位机之间使用modbus协议进行串口通信。通过串口与其他设备进行通信，传递数据。可以理解为电脑和键盘、鼠标通信。
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串口连接

android端连接串口方法，其实就是设置串口的参数，打开底层的串口文件，android开发的朋友也可以让驱动人员帮忙写，当然谷歌也有官方框架，这里我使用的是第三方框架，参考的是这位大神的文章
参考大神链接
调试精灵
首先在gradle配置：

implementation 'tp.xmaihh:serialport:2.1'

全部源码

import java.io.ByteArrayOutputStream;

public class ByteArrayWriter extends ByteArrayOutputStream {
    public ByteArrayWriter() {
        super();
    }

    public void writeInt8(byte b)
    {
        this.write(b);
    }

    public void writeInt8(int b)
    {
        this.write((byte)b);
    }

    public void writeInt16(int n) {
        byte[] bytes = ByteUtil.fromInt16(n);
        this.write(bytes, 0, bytes.length);
    }

    public void writeInt16Reversal(int n){
        byte[] bytes=ByteUtil.fromInt16Reversal(n);
        this.write(bytes,0,bytes.length);
    }

    public void writeInt32(int n) {
        byte[] bytes = ByteUtil.fromInt32(n);
        this.write(bytes, 0, bytes.length);
    }

    public void writeBytes(byte[] bs,int len){
        this.write(bs,0,len);
    }

}

public class ByteUtil {

    public static String toHexString(byte[] input, String separator) {
        if (input == null) return null;

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < input.length; i++) {
            if (separator != null && sb.length() > 0) {
                sb.append(separator);
            }
            String str = Integer.toHexString(input[i] & 0xff);
            if (str.length() == 1) str = "0" + str;
            sb.append(str);
        }
        return sb.toString();
    }

    public static String toHexString(byte[] input) {
        return toHexString(input, " ");
    }

    public static byte[] fromInt32(int input) {
        byte[] result = new byte[4];
        result[3] = (byte) (input >> 24 & 0xFF);
        result[2] = (byte) (input >> 16 & 0xFF);
        result[1] = (byte) (input >> 8 & 0xFF);
        result[0] = (byte) (input & 0xFF);
        return result;
    }

    public static byte[] fromInt32R(int input) {
        byte[] result = new byte[4];
        result[0] = (byte) ((input >> 24) & 0xFF);
        result[1] = (byte) ((input >> 16) & 0xFF);
        result[2] = (byte) ((input >> 8) & 0xFF);
        result[3] = (byte) (input & 0xFF);
        return result;
    }

    public static byte[] fromInt16(int input) {
        byte[] result = new byte[2];
        result[0] = (byte) (input >> 8 & 0xFF);
        result[1] = (byte) (input & 0xFF);
        return result;
    }

    public static int fromBytes(byte a, byte b) {
        return ((a & 0xFF) << 8) + (b & 0xFF);
    }

    public static byte[] fromInt16Reversal(int input) {
        byte[] result = new byte[2];
        result[1] = (byte) (input >> 8 & 0xFF);
        result[0] = (byte) (input & 0xFF);
        return result;
    }

    public static int byteArrayToInt16(byte[] bytes) {
        int value = 0;
        for (int i = 0; i < 2; i++) {
            int shift = (1 - i) * 8;
            value += (bytes[i] & 0xFF) << shift;
        }
        return value;
    }

    /**
     * byte[]转int
     *
     * @param bytes 需要转换成int的数组
     * @return int值
     */
    public static int byteArrayToInt(byte[] bytes) {
        int value = 0;
        for (int i = 0; i < 4; i++) {
            int shift = (3 - i) * 8;
            value += (bytes[i] & 0xFF) << shift;
        }
        return value;
    }

}

public class CRC16 {
    private static final byte[] crc16_tab_h = { (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40,
            (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x01, (byte) 0xC0, (byte) 0x80,
            (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0,
            (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x00,
            (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81,
            (byte) 0x40, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0,
            (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01,
            (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80,
            (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x00, (byte) 0xC1,
            (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00,
            (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81,
            (byte) 0x40, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0,
            (byte) 0x80, (byte) 0x41, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00,
            (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x00, (byte) 0xC1, (byte) 0x81,
            (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x01, (byte) 0xC0,
            (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x00,
            (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80,
            (byte) 0x41, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1,
            (byte) 0x81, (byte) 0x40, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01,
            (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80,
            (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x00, (byte) 0xC1,
            (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00,
            (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81,
            (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1,
            (byte) 0x81, (byte) 0x40, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x01,
            (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41,
            (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40, (byte) 0x00, (byte) 0xC1, (byte) 0x81,
            (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1,
            (byte) 0x81, (byte) 0x40, (byte) 0x01, (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x01,
            (byte) 0xC0, (byte) 0x80, (byte) 0x41, (byte) 0x00, (byte) 0xC1, (byte) 0x81, (byte) 0x40 };

    private static final byte[] crc16_tab_l = { (byte) 0x00, (byte) 0xC0, (byte) 0xC1, (byte) 0x01,
            (byte) 0xC3, (byte) 0x03, (byte) 0x02, (byte) 0xC2, (byte) 0xC6, (byte) 0x06, (byte) 0x07,
            (byte) 0xC7, (byte) 0x05, (byte) 0xC5, (byte) 0xC4, (byte) 0x04, (byte) 0xCC, (byte) 0x0C,
            (byte) 0x0D, (byte) 0xCD, (byte) 0x0F, (byte) 0xCF, (byte) 0xCE, (byte) 0x0E, (byte) 0x0A,
            (byte) 0xCA, (byte) 0xCB, (byte) 0x0B, (byte) 0xC9, (byte) 0x09, (byte) 0x08, (byte) 0xC8,
            (byte) 0xD8, (byte) 0x18, (byte) 0x19, (byte) 0xD9, (byte) 0x1B, (byte) 0xDB, (byte) 0xDA,
            (byte) 0x1A, (byte) 0x1E, (byte) 0xDE, (byte) 0xDF, (byte) 0x1F, (byte) 0xDD, (byte) 0x1D,
            (byte) 0x1C, (byte) 0xDC, (byte) 0x14, (byte) 0xD4, (byte) 0xD5, (byte) 0x15, (byte) 0xD7,
            (byte) 0x17, (byte) 0x16, (byte) 0xD6, (byte) 0xD2, (byte) 0x12, (byte) 0x13, (byte) 0xD3,
            (byte) 0x11, (byte) 0xD1, (byte) 0xD0, (byte) 0x10, (byte) 0xF0, (byte) 0x30, (byte) 0x31,
            (byte) 0xF1, (byte) 0x33, (byte) 0xF3, (byte) 0xF2, (byte) 0x32, (byte) 0x36, (byte) 0xF6,
            (byte) 0xF7, (byte) 0x37, (byte) 0xF5, (byte) 0x35, (byte) 0x34, (byte) 0xF4, (byte) 0x3C,
            (byte) 0xFC, (byte) 0xFD, (byte) 0x3D, (byte) 0xFF, (byte) 0x3F, (byte) 0x3E, (byte) 0xFE,
            (byte) 0xFA, (byte) 0x3A, (byte) 0x3B, (byte) 0xFB, (byte) 0x39, (byte) 0xF9, (byte) 0xF8,
            (byte) 0x38, (byte) 0x28, (byte) 0xE8, (byte) 0xE9, (byte) 0x29, (byte) 0xEB, (byte) 0x2B,
            (byte) 0x2A, (byte) 0xEA, (byte) 0xEE, (byte) 0x2E, (byte) 0x2F, (byte) 0xEF, (byte) 0x2D,
            (byte) 0xED, (byte) 0xEC, (byte) 0x2C, (byte) 0xE4, (byte) 0x24, (byte) 0x25, (byte) 0xE5,
            (byte) 0x27, (byte) 0xE7, (byte) 0xE6, (byte) 0x26, (byte) 0x22, (byte) 0xE2, (byte) 0xE3,
            (byte) 0x23, (byte) 0xE1, (byte) 0x21, (byte) 0x20, (byte) 0xE0, (byte) 0xA0, (byte) 0x60,
            (byte) 0x61, (byte) 0xA1, (byte) 0x63, (byte) 0xA3, (byte) 0xA2, (byte) 0x62, (byte) 0x66,
            (byte) 0xA6, (byte) 0xA7, (byte) 0x67, (byte) 0xA5, (byte) 0x65, (byte) 0x64, (byte) 0xA4,
            (byte) 0x6C, (byte) 0xAC, (byte) 0xAD, (byte) 0x6D, (byte) 0xAF, (byte) 0x6F, (byte) 0x6E,
            (byte) 0xAE, (byte) 0xAA, (byte) 0x6A, (byte) 0x6B, (byte) 0xAB, (byte) 0x69, (byte) 0xA9,
            (byte) 0xA8, (byte) 0x68, (byte) 0x78, (byte) 0xB8, (byte) 0xB9, (byte) 0x79, (byte) 0xBB,
            (byte) 0x7B, (byte) 0x7A, (byte) 0xBA, (byte) 0xBE, (byte) 0x7E, (byte) 0x7F, (byte) 0xBF,
            (byte) 0x7D, (byte) 0xBD, (byte) 0xBC, (byte) 0x7C, (byte) 0xB4, (byte) 0x74, (byte) 0x75,
            (byte) 0xB5, (byte) 0x77, (byte) 0xB7, (byte) 0xB6, (byte) 0x76, (byte) 0x72, (byte) 0xB2,
            (byte) 0xB3, (byte) 0x73, (byte) 0xB1, (byte) 0x71, (byte) 0x70, (byte) 0xB0, (byte) 0x50,
            (byte) 0x90, (byte) 0x91, (byte) 0x51, (byte) 0x93, (byte) 0x53, (byte) 0x52, (byte) 0x92,
            (byte) 0x96, (byte) 0x56, (byte) 0x57, (byte) 0x97, (byte) 0x55, (byte) 0x95, (byte) 0x94,
            (byte) 0x54, (byte) 0x9C, (byte) 0x5C, (byte) 0x5D, (byte) 0x9D, (byte) 0x5F, (byte) 0x9F,
            (byte) 0x9E, (byte) 0x5E, (byte) 0x5A, (byte) 0x9A, (byte) 0x9B, (byte) 0x5B, (byte) 0x99,
            (byte) 0x59, (byte) 0x58, (byte) 0x98, (byte) 0x88, (byte) 0x48, (byte) 0x49, (byte) 0x89,
            (byte) 0x4B, (byte) 0x8B, (byte) 0x8A, (byte) 0x4A, (byte) 0x4E, (byte) 0x8E, (byte) 0x8F,
            (byte) 0x4F, (byte) 0x8D, (byte) 0x4D, (byte) 0x4C, (byte) 0x8C, (byte) 0x44, (byte) 0x84,
            (byte) 0x85, (byte) 0x45, (byte) 0x87, (byte) 0x47, (byte) 0x46, (byte) 0x86, (byte) 0x82,
            (byte) 0x42, (byte) 0x43, (byte) 0x83, (byte) 0x41, (byte) 0x81, (byte) 0x80, (byte) 0x40 };

    /**
     * 计算CRC16校验
     *
     * @param data
     *            需要计算的数组
     * @return CRC16校验值
     */
    public static int compute(byte[] data) {
        return compute(data, 0, data.length);
    }

    /**
     * 计算CRC16校验
     *
     * @param data
     *            需要计算的数组
     * @param offset
     *            起始位置
     * @param len
     *            长度
     * @return CRC16校验值
     */
    public static int compute(byte[] data, int offset, int len) {
        return compute(data, offset, len, 0xffff);
    }

    /**
     * 计算CRC16校验
     *
     * @param data
     *            需要计算的数组
     * @param offset
     *            起始位置
     * @param len
     *            长度
     * @param preval
     *            之前的校验值
     * @return CRC16校验值
     */
    public static int compute(byte[] data, int offset, int len, int preval) {
        int ucCRCHi = (preval & 0xff00) >> 8;
        int ucCRCLo = preval & 0x00ff;
        int iIndex;
        for (int i = 0; i < len; ++i) {
            iIndex = (ucCRCLo ^ data[offset + i]) & 0x00ff;
            ucCRCLo = ucCRCHi ^ crc16_tab_h[iIndex];
            ucCRCHi = crc16_tab_l[iIndex];
        }
        int result=((ucCRCHi & 0x00ff) << 8) | (ucCRCLo & 0x00ff) & 0xffff;
        return result;
    }
}

import android.text.TextUtils;

public class ModbusError extends Exception {
    private int code;

    public ModbusError(int code, String message) {
        super(!TextUtils.isEmpty(message) ? message : "Modbus Error: Exception code = " + code);
        this.code = code;
    }

    public ModbusError(int code) {
        this(code, null);
    }

    public ModbusError(ModbusErrorType type, String message) {
        super(type.name() + ": " + message);
    }

    public ModbusError(String message) {
        super(message);
    }

    public int getCode() {
        return this.code;
    }
}

/**
 * 常见的Modbus通讯错误
 */
public enum ModbusErrorType {
    ModbusError,
    ModbusFunctionNotSupportedError,
    ModbusDuplicatedKeyError,
    ModbusMissingKeyError,
    ModbusInvalidBlockError,
    ModbusInvalidArgumentError,
    ModbusOverlapBlockError,
    ModbusOutOfBlockError,
    ModbusInvalidResponseError,
    ModbusInvalidRequestError,
    ModbusTimeoutError
}

/**
 * 功能码（十进制显示）
 */
public class ModbusFunction {

    //读线圈寄存器
    public static final int READ_COILS = 1;

    //读离散输入寄存器
    public static final int READ_DISCRETE_INPUTS = 2;

    //读保持寄存器
    public static final int READ_HOLDING_REGISTERS = 3;

    //读输入寄存器
    public static final int READ_INPUT_REGISTERS = 4;

    //写单个线圈寄存器
    public static final int WRITE_SINGLE_COIL = 5;

    //写单个保持寄存器
    public static final int WRITE_SINGLE_REGISTER = 6;

    //写入多个线圈寄存器
    public static final int WRITE_COILS = 15;

    //写入多个保持寄存器
    public static final int WRITE_HOLDING_REGISTERS = 16;
}

import tp.xmaihh.serialport.SerialHelper;

public class ModbusRtuMaster {

    private SerialHelper serialHelper;

    //第1种使用serialport第三方库
    public ModbusRtuMaster(SerialHelper serialHelper) {
        this.serialHelper = serialHelper;
    }


    /**
     * 组装Modbus RTU消息帧
     * @param slave 从站地址号
     * @param function_code 功能码
     * @param starting_address 读取寄存器起始地址 / 写入寄存器地址 / 写入寄存器起始地址
     * @param quantity_of_x 读取寄存器个数 / 写入寄存器个数
     * @param output_value 需要写入单个寄存器的数值
     * @param output_values 需要写入多个寄存器的数组
     * @return 将整个消息帧转成byte[]
     * @throws ModbusError Modbus错误
     */
    synchronized private byte[] execute(int slave, int function_code, int starting_address, int quantity_of_x,
                                        int output_value, int[] output_values) throws ModbusError {
        //检查参数是否符合协议规定
        if (slave < 0 || slave > 0xff) {
            throw new ModbusError(ModbusErrorType.ModbusInvalidArgumentError, "Invalid slave " + slave);
        }
        if (starting_address < 0 || starting_address > 0xffff) {
            throw new ModbusError(ModbusErrorType.ModbusInvalidArgumentError, "Invalid starting_address " + starting_address);
        }
        if (quantity_of_x < 1 || quantity_of_x > 0xff) {
            throw new ModbusError(ModbusErrorType.ModbusInvalidArgumentError, "Invalid quantity_of_x " + quantity_of_x);
        }

        // 构造request
        ByteArrayWriter request = new ByteArrayWriter();
        //写入从站地址号
        request.writeInt8(slave);
        //根据功能码组装数据区
        //如果为读取寄存器指令
        if (function_code == ModbusFunction.READ_COILS || function_code == ModbusFunction.READ_DISCRETE_INPUTS
                || function_code == ModbusFunction.READ_INPUT_REGISTERS || function_code == ModbusFunction.READ_HOLDING_REGISTERS) {
            request.writeInt8(function_code);
            request.writeInt16(starting_address);
            request.writeInt16(quantity_of_x);

        } else if (function_code == ModbusFunction.WRITE_SINGLE_COIL || function_code == ModbusFunction.WRITE_SINGLE_REGISTER) {//写单个寄存器指令
            if (function_code == ModbusFunction.WRITE_SINGLE_COIL)
                if (output_value != 0) output_value = 0xff00;//如果为线圈寄存器（写1时为 FF 00,写0时为00 00）
            request.writeInt8(function_code);
            request.writeInt16(starting_address);
            request.writeInt16(output_value);

        } else if (function_code == ModbusFunction.WRITE_COILS) {//写多个线圈寄存器
            request.writeInt8(function_code);
            request.writeInt16(starting_address);
            request.writeInt16(quantity_of_x);

            //计算写入字节数
            int writeByteCount = (quantity_of_x / 8) + 1;/// 满足关系-> (w /8) + 1
            //写入数量 == 8 ,则写入字节数为1
            if (quantity_of_x % 8 == 0) {
                writeByteCount -= 1;
            }
            request.writeInt8(writeByteCount);

            int index = 0;
            //如果写入数据数量 > 8 ，则需要拆分开来
            int start = 0;//数组开始位置
            int end = 7;//数组结束位置
            int[] splitData = new int[8];
            //循环写入拆分数组，直到剩下最后一组 元素个数 <= 8 的数据
            while (writeByteCount > 1) {
                writeByteCount--;
                int sIndex = 0;
                for (index = start; index <= end; index++){
                    splitData [sIndex++] = output_values[index];
                }
                //数据反转 对于是否要反转要看你传过来的数据，如果高低位顺序正确则不用反转
                splitData = reverseArr(splitData);
                //写入拆分数组
                request.writeInt8(toDecimal(splitData));
                start = index;
                end += 8;
            }
            //写入最后剩下的数据
            int last = quantity_of_x - index;
            int[] tData = new int[last];
            System.arraycopy(output_values, index, tData, 0, last);
            //数据反转 对于是否要反转要看你传过来的数据，如果高低位顺序正确则不用反转
            tData = reverseArr(tData);
            request.writeInt8(toDecimal(tData));
        } else if (function_code == ModbusFunction.WRITE_HOLDING_REGISTERS) {//写多个保持寄存器
            request.writeInt8(function_code);
            request.writeInt16(starting_address);
            request.writeInt16(quantity_of_x);
            request.writeInt8(2 * quantity_of_x);
            //写入数据
            for (int v : output_values) {
                request.writeInt16(v);
            }
        } else {
            throw new ModbusError(ModbusErrorType.ModbusFunctionNotSupportedError, "Not support function " + function_code);
        }
        byte[] bytes = request.toByteArray();
        //计算CRC校验码
        int crc = CRC16.compute(bytes);
        request.writeInt16Reversal(crc);
        bytes = request.toByteArray();
        return bytes;
    }

    /**
     * 读多个线圈寄存器
     * @param slave 从站地址
     * @param startAddress 起始地址
     * @param numberOfPoints 读取线圈寄存器个数
     * @throws ModbusError Modbus错误
     */
    public void readCoils(int slave, int startAddress, int numberOfPoints) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.READ_COILS, startAddress, numberOfPoints, 0, null);
        this.serialHelper.send(sendBytes);
    }
    //读单个线圈寄存器
    public void readCoil(int slave, int address) throws ModbusError {
        readCoils(slave, address, 1);
    }

    /**
     * 读多个保持寄存器
     * @param slave 从站地址
     * @param startAddress 起始地址
     * @param numberOfPoints 读取保持寄存器个数
     * @throws ModbusError Modbus错误
     */
    public void readHoldingRegisters(int slave, int startAddress, int numberOfPoints) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.READ_HOLDING_REGISTERS, startAddress, numberOfPoints, 0, null);
        this.serialHelper.send(sendBytes);
    }

    //读单个保持寄存器
    public void readHoldingRegister(int slave, int address) throws ModbusError {
        readHoldingRegisters(slave, address, 1);
    }


    /**
     * 读多个输入寄存器
     * @param slave 从站地址
     * @param startAddress 起始地址
     * @param numberOfPoints 读取输入寄存器个数
     * @throws ModbusError Modbus错误
     */
    public void readInputRegisters(int slave, int startAddress, int numberOfPoints) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.READ_INPUT_REGISTERS, startAddress, numberOfPoints, 0, null);
        this.serialHelper.send(sendBytes);
    }
    //读单个输入寄存器
    public void readInputRegister(int slave, int address) throws ModbusError {
        readInputRegisters(slave, address, 1);
    }

    /**
     * 读多个离散输入寄存器
     * @param slave 从站地址
     * @param startAddress 起始地址
     * @param numberOfPoints 读取离散输入寄存器个数
     * @throws ModbusError Modbus错误
     */
    public void readDiscreteInputs(int slave, int startAddress, int numberOfPoints) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.READ_DISCRETE_INPUTS, startAddress, numberOfPoints, 0, null);
        this.serialHelper.send(sendBytes);
    }
    //读单个离散输入寄存器
    public void readDiscreteInput(int slave, int address) throws ModbusError {
        readDiscreteInputs(slave, address, 1);
    }

    /**
     * 写单个线圈寄存器
     * @param slave 从站地址
     * @param address 写入寄存器地址
     * @param value 写入值（true/false)
     * @throws ModbusError Modbus错误
     */
    public void writeSingleCoil(int slave, int address, boolean value) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.WRITE_SINGLE_COIL, address, 1, value ? 1 : 0, null);
        this.serialHelper.send(sendBytes);
    }

    /**
     * 写单个保持寄存器
     * @param slave 从站地址
     * @param address 写入寄存器地址
     * @param value 写入值
     * @throws ModbusError Modbus错误
     */
    public void writeSingleRegister(int slave, int address, int value) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.WRITE_SINGLE_REGISTER, address, 1, value, null);
        this.serialHelper.send(sendBytes);
    }

    /**
     *   写入多个保持寄存器
     * @param slave 从站地址
     * @param address 写入寄存器地址
     * @param sCount 写入寄存器个数
     * @param data 写入数据
     * @throws ModbusError
     */
    public void writeHoldingRegisters(int slave, int address, int sCount, int [] data) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.WRITE_HOLDING_REGISTERS, address, sCount, 0, data);
        this.serialHelper.send(sendBytes);
    }

    /**
     *   写入多个位
     * @param slave 从站地址
     * @param address 写入寄存器地址
     * @param bCount 写入寄存器个数
     * @param data 写入数据{1,0}
     * @throws ModbusError
     */
    public void writeCoils(int slave, int address,int bCount, int [] data) throws ModbusError {
        byte[] sendBytes = execute(slave, ModbusFunction.WRITE_COILS, address, bCount, 0, data);
        this.serialHelper.send(sendBytes);
    }



    //将数组反转
    public static int[] reverseArr(int[] arr) {
        int[] tem = new int[arr.length];
        for(int i=0; i<arr.length; i++) {
            tem[i] = arr[arr.length-1-i];
        }
        return tem;
    }

    //将int[1,0,0,1,1,0]数组转换为十进制数据
    public static int toDecimal(int[] data){
        int result = 0;
        if(data != null){
            StringBuilder sData = new StringBuilder();
            for (int d : data){
                sData.append(d);
            }
            try {
                result = Integer.parseInt(sData.toString(), 2);
            } catch (NumberFormatException e) {
                result = -1;
            }

        }
        return result;
    }

}

public class ModbusUtil {

    ModbusRtuMaster modbusRtuMaster;
    SerialHelper serialHelper;

    public void start() {
        try {

            //初始化SerialHelper对象，设定串口名称和波特率
            serialHelper = new SerialHelper("/dev/ttySAC0", 115200) {
                @Override
                protected void onDataReceived(ComBean paramComBean) {
                    //根据自己的业务自行处理接收的数据
                    L.i("数据1==" + Arrays.toString(paramComBean.bRec) + "===" + paramComBean.bRec.length + "==" + paramComBean.bRec[0] + "==" + paramComBean.bRec[1]);
                    //[1, 3, 0, 1, 0, 1, -43, -54]
                    //如果是负数，则十进制结果为256+负数，如256+(-54)=202

					//这里需要你对接收到的数据进行处理，这里我举个例子，收到数据后，返回一个数据，
                    当然正式上线肯定是需要按响应报文规则去回复的
                    new Thread(() -> {
                        try {
                            modbusRtuMaster.writeSingleRegister(1, 1, 3);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }).start();
                }
            };

            /*
             * 默认的BaseStickPackageHelper将接收的数据扩展成64位，一般用不到这么多位
             * 我这里重新设定一个自适应数据位数的
             * 这里将64位改为自适应位
             */
            serialHelper.setStickPackageHelper(is -> {
                try {
                    int available = is.available();
                    if (available > 0) {
                        byte[] buffer = new byte[available];
                        int size = is.read(buffer);
                        if (size > 0) {
                            return buffer;
                        }
                    } else {
                        SystemClock.sleep(50);
                    }

                } catch (IOException e) {
                    e.printStackTrace();
                }
                return null;
            });

            new Thread(() -> {
                try {
                    serialHelper.open();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }).start();

            modbusRtuMaster = new ModbusRtuMaster(serialHelper);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

使用

ModbusUtil m = new ModbusUtil();
        m.start();

我们直接调用ModbusUtil的start()即可打开串口，这里注意/dev/ttySAC0是串口文件名称，115200是波特率，设置好串口参数，我们使用serialHelper.open()方法即可打开串口了，然后是通过文件流去发送数据，结合modbus协议，我们要发送一个报文，将数据写入输出流，比如我们读线圈，报文格式是

也就是：从站地址 功能码 起始地址 线圈数量 校验码
我们注意起始地址、线圈数量、校验码是16位字节，其他是8位
这里ByteArrayWriter类已经给我们封装好方法了，去写入writeInt8或者writeInt16即可。
紧接着我们使用mobdus调试工具进行测试。
使用以上源码，即可调试出下图结果

这里我收到数据后，回复了modbusRtuMaster.writeSingleRegister(1, 1, 3);，然后接收端收到了03，至此，完成了发送和接收。另外需要注意的是当别人发送数据给你时需要按响应报文格式去回复。