基于C++的Modbus协议解析类

使用示例：

示例1

生成读取寄存器的报文

unsigned char  dataBuff[128] = {0}; 
ModBus modbus(dataBuff, sizeof(dataBuff)); 
modbus.setMeterNumber(0x01);
modbus.setFunctionCode(ModBus::Read_Coil);
modbus.setStartRegister(0x13);
modbus.setRegisterCount(0x13);

int nCmdLen = 0;
if(!modbus.getCmd(nCmdLen))
{
	//todo process error
}

示例2

生成写入寄存器的报文

unsigned char  dataBuff[128] = {0}; 
ModBus modbus(dataBuff, sizeof(dataBuff)); 
modbus.setMeterNumber(0x01);
modbus.setFunctionCode(ModBus::Write_Serval_Reg);
modbus.setStartRegister(0x01);
modbus.setRegisterCount(0x02);
modbus.setRegisterValue(0x01, 0x3412);
modbus.setRegisterValue(0x01, 0x102);

int nCmdLen = 0;
if(!modbus.getCmd(nLen)
{
	//todo process error
}

示例3

解析读取寄存器的报文

unsigned char dataBuff[] = {0xFF, 0x04, 0x03, 0x06, 0x02, 0x2B, 0x00, 0x00, 0x00, 0x64, 0x3A, 0x2A};
ModBus modbus(dataBuff, sizeof(dataBuff)); 
int nStartIndex, nCmdLen;
if(modbus.parseCmd(nStartIndex, nCmdLen))
{
    //nStartIndex应该等1，nCmdLen应该等于11
    unsigned char nMeterNumber = modbus.getMeterNumber(); //等于0x04
    unsigned char nFunctionCode = modbus.getFunctionCode(); //等于0x03
    unsigned char nDataLen = modbus.getDataLength(); //等于6

    unsigned short nValue;
    if(modbus.getRegisterValue(0, nValue))
    {
        //nValue 应该等于0x22B
    }
}