我有一个条形码阅读器，它连接到RS232串口的PC上。我正在编写一个C ++代码来向条形码扫描器发送命令并将响应返回给PC。目前程序可以正确地向设备发送数据，但是无法读取条形码扫描器的响应。在这种情况下，一旦我们向条形码阅读器发送命令，它将以肯定或否定确认回复。
e.g:- Send BEEP command.
1. Host(PC) send a BEEP command to barcode scanner
2. Barcode scanner make a beep sound and send the acknowledgement back
to host (PC)
3. Host (PC) read the acknowledgement
在下面的代码中，前两步正常工作，但我无法正确编写第三个。请有人帮我纠正我的源代码，以异步方式读取条形码扫描器的响应。
的main.cpp
#include <iostream>
extern "C"
{
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
}
#include "DeviceRS232.h"
#include "Message.h"
int main()
{
unsigned char recvBuffer[257];
unsigned char ledOn[] = {0x05, 0xE7, 0x04, 0x00, 0x0D, 0x00};
unsigned char SSIBuffer[] = {0x00, 0xC6, 0x04, 0x08, 0x11, 0xEE, 0x01};
unsigned char requestRevision[] = {0x00, 0x04, 0xA3, 0x04, 0x00};
unsigned char sendBeep[] = {0x00, 0xE6, 0x04, 0x00, 0x05};
Message beepCommand(sendBeep, sizeof(sendBeep)/sizeof(sendBeep[0]));
std::cout << "*********************************************************" << std::endl << std::endl;
DeviceRS232 dev_rs232;
dev_rs232.setDefaultAttributes();
dev_rs232.openSerialPort();
// Send BEEP command several times.
std::cout << "---Start sending beep---" << std::endl;
for(int x=0; x<1; x++)
{
int sizeSent = dev_rs232.sendDataBuffer(beepCommand.getCommandData(), beepCommand.getLen());
if( sizeSent > 0)
{
std::cout << "Data sent: " << sizeSent << std::endl;
}
memset(recvBuffer, 0, sizeof(recvBuffer));
int recvSize = dev_rs232.receiveDataBuffer(recvBuffer, sizeof(recvBuffer));
std::cout << "Date Received, Data: " << recvBuffer << " Size: " << recvSize << std::endl;
sleep(2);
/**
while(true)
{
memset(recvBuffer, 0, sizeof(recvBuffer));
int recvSize = dev_rs232.receiveDataBuffer(recvBuffer, sizeof(recvBuffer));
if(recvSize > 0)
std::cout << "Date Received, Data: " << recvBuffer << " Size: " << recvSize << std::endl;
sleep(2);
}*/
}
std::cout << "---End sending beep-----\n" << std::endl;
dev_rs232.closeSerialPort();
std::cout << "*********************************************************" << std::endl;
return 0;
}
Message.h
#ifndef MESSAGE_H
#define MESSAGE_H
#include <iostream>
#include <string>
#include <numeric>
extern "C"
{
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
}
class Message
{
public:
Message(); // default constructor
virtual ~Message(); // destructor
Message(const std::basic_string<unsigned char> msg) : commandMsg(msg)
{
printf("msg[0]:%x\n", msg[4]);
std::cout << "length: " << commandMsg.length() << std::endl;
//commandMsg[0] = commandMsg.length();
appendChecksum();
};
Message(const unsigned char *msg, int msglen) : commandMsg(msg, msglen)
{
commandMsg[0] = commandMsg.length();
appendChecksum();
};
const unsigned char *getCommandData() const
{
return commandMsg.c_str();
}
int getLen() const
{
return commandMsg.length();
}
protected:
private:
int appendChecksum();
std::basic_string<unsigned char> commandMsg;
};
#endif // MESSAGE_H
Message.cpp
#include "Message.h"
Message::Message()
{
//ctor
}
Message::~Message()
{
//dtor
}
int Message::appendChecksum()
{
int sum = -std::accumulate(commandMsg.begin(), commandMsg.end(), 0);
commandMsg.push_back(0xFF & (sum >> 8));
commandMsg.push_back(0xFF & sum);
}
DeviceRS232.h
#ifndef DEVICERS232_H
#define DEVICERS232_H
extern "C"
{
#include <stdio.h>
#include <string.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <limits.h>
#include <stdlib.h>
}
#include <string>
#define MAX_SERIAL_PORT_NO 30
class DeviceRS232
{
public:
DeviceRS232();
virtual ~DeviceRS232();
int fdRS232; // file descriptor for the serial port
void setSerialPort(std::string sp);
void setBaudRate(long baud);
void setDataBits(int dataBit);
void setStopBits(int stopBit);
void setNumberOfParityBits(int nparityBits);
void setDefaultAttributes();
long getBaudRate();
std::string getSerialPort();
int openSerialPort();
int readUserConfiguration();
int sendDataBuffer(const unsigned char *dataBuffer, size_t bufferSize);
int receiveDataBuffer(unsigned char *dataBuffer, size_t bufferSize);
void closeSerialPort();
protected:
std::string serialPort; // Serial port like /dev/ttyS0
long baudRate; // Scanner baud rate
int dataBits; // data bits
int stopBits; // stop bits
int numberOfParityBits; // number of parity bits
termios oldSerialPortSetting; // Current values of termios structure for /dev/ttyS0
termios newSerialPortSetting; // new termios attributes for /dev/ttyS0
private:
};
#endif // DEVICERS232_H
DeviceRS232.cpp
#include "DeviceRS232.h"
DeviceRS232::DeviceRS232()
{
//ctor
}
DeviceRS232::~DeviceRS232()
{
//dtor
}
void DeviceRS232::setSerialPort(std::string sp)
{
serialPort = sp;
}
void DeviceRS232::setBaudRate(long baud)
{
baudRate = baud;
}
void DeviceRS232::setDataBits(int dataBit)
{
dataBits = dataBit;
}
void DeviceRS232::setStopBits(int stopBit)
{
stopBits = stopBit;
}
void DeviceRS232::setNumberOfParityBits(int nparityBits)
{
numberOfParityBits = nparityBits;
}
void DeviceRS232::setDefaultAttributes()
{
std::string sp = "/dev/ttyS0";
long baud = 9600;
int dataBit = 1;
int stopBit = 1;
int nparityBits = 0;
setSerialPort(sp);
setBaudRate(baud);
setDataBits(dataBit);
setStopBits(stopBit);
setNumberOfParityBits(nparityBits);
}
long DeviceRS232::getBaudRate()
{
return baudRate;
}
std::string DeviceRS232::getSerialPort()
{
return serialPort;
}
int DeviceRS232::openSerialPort()
{
int fd, baudr, status, portStatus;
setDefaultAttributes();
switch(getBaudRate())
{
case 50 : baudr = B50;
break;
case 75 : baudr = B75;
break;
case 110 : baudr = B110;
break;
case 134 : baudr = B134;
break;
case 150 : baudr = B150;
break;
case 200 : baudr = B200;
break;
case 300 : baudr = B300;
break;
case 600 : baudr = B600;
break;
case 1200 : baudr = B1200;
break;
case 1800 : baudr = B1800;
break;
case 2400 : baudr = B2400;
break;
case 4800 : baudr = B4800;
break;
case 9600 : baudr = B9600;
break;
case 19200 : baudr = B19200;
break;
case 38400 : baudr = B38400;
break;
case 57600 : baudr = B57600;
break;
case 115200 : baudr = B115200;
break;
case 230400 : baudr = B230400;
break;
case 460800 : baudr = B460800;
break;
case 500000 : baudr = B500000;
break;
case 576000 : baudr = B576000;
break;
case 921600 : baudr = B921600;
break;
case 1000000 : baudr = B1000000;
break;
default : printf("invalid baudrate\n");
return(1);
break;
}
// Open serial port
fd = open(getSerialPort().c_str(), O_RDWR | O_NOCTTY | O_NDELAY);
if(fd == -1)
{
printf("Unable to open serial port...\n");
perror(getSerialPort().c_str());
return 1;
}
fdRS232 = fd;
fcntl(fdRS232, F_SETFL, FNDELAY);
status = tcgetattr(fdRS232, &oldSerialPortSetting);
if(status == -1)
{
close(fdRS232);
printf("Unable to get serial port attributes...\n");
return 1;
}
memset(&newSerialPortSetting, 0, sizeof(newSerialPortSetting));
newSerialPortSetting.c_cflag = baudr | CS8 | CLOCAL | CREAD; //
newSerialPortSetting.c_iflag = IGNPAR;
newSerialPortSetting.c_oflag = 0;
newSerialPortSetting.c_lflag = 0;
newSerialPortSetting.c_cc[VMIN] = 0;
newSerialPortSetting.c_cc[VTIME] = 0;
status = tcsetattr(fdRS232, TCSANOW, &newSerialPortSetting);
if(status==-1)
{
close(fdRS232);
perror("unable to adjust portsettings ");
return 1;
}
// Get the status of opened serial port
if(ioctl(fdRS232, TIOCMGET, &portStatus) == -1)
{
perror("Unable to get port status");
return 1;
}
// Tern on DTR and RTS
portStatus |= TIOCM_DTR;
portStatus |= TIOCM_RTS;
// Set the status of the port with new DTR, RTS values
if(ioctl(fdRS232, TIOCMSET, &portStatus) == -1)
{
perror("Unable to set port status...");
return 1;
}
return 0;
}
int DeviceRS232::sendDataBuffer(const unsigned char *dataBuffer, size_t bufferSize)
{
return write(fdRS232, dataBuffer, bufferSize);
}
int DeviceRS232::receiveDataBuffer(unsigned char *dataBuffer, size_t bufferSize)
{
/**int recvSize = 0;
recvSize = read(fdRS232, dataBuffer, bufferSize);
return recvSize;*/
unsigned char recvBuffer[255];
unsigned char *ptrChar;
int nBytes;
ptrChar = recvBuffer;
memset(recvBuffer, 0x00, sizeof(recvBuffer));
while((nBytes = read(fdRS232, ptrChar, recvBuffer+sizeof(recvBuffer) - ptrChar -1)) > 0)
{
ptrChar += nBytes;
//printf("while - %d\n", nBytes);
}
//printf("recvBuffer : %x\n", recvBuffer[0]);
//printf("recvBuffer : %x\n", recvBuffer[1]);
//printf("recvBuffer : %x\n", recvBuffer[2]);
//printf("recvBuffer : %x\n", recvBuffer[3]);
//printf("recvBuffer : %x\n", recvBuffer[4]);
dataBuffer = recvBuffer;
return nBytes;
}
void DeviceRS232::closeSerialPort()
{
int portStatus;
if(ioctl(fdRS232, TIOCMGET, &portStatus) == -1)
{
perror("Unable to get the port status");
}
// Tern off DTR and RTS
portStatus &= ~TIOCM_DTR;
portStatus &= ~TIOCM_RTS;
// Set the status of the port with new DTR, RTS values
if(ioctl(fdRS232, TIOCMSET, &portStatus) == -1)
{
perror("Unable to set port status...");
}
close(fdRS232);
}
我的错误方法是int DeviceRS232::receiveDataBuffer(unsigned char *dataBuffer, size_t bufferSize)
以下是控制台输出：
*********************************************************
---Start sending beep---
Data sent: 7
Date Received, Data: Size: 0
---End sending beep-----
*********************************************************
Process returned 0 (0x0) execution time : 2.004 s
Press ENTER to continue.
答案 0 :(得分：2)
正如其他人所说，一个可疑区域是您要发送的字节数。条形码阅读器可能只需要命令中的字节数而不是更多，而不是总是发送257个字节。
此外，您的代码还有许多重复操作，用于计算消息末尾的校验和。这表明课程将有助于简化设计。那么，这是一个Message类用于此目的：
#include <vector>
#include <numeric>
#include <string>
class Message
{
public:
Message(const std::basic_string<unsigned char> msg) : mymsg(msg) {
mymsg[0] = mymsg.length(); appendChecksum(); };
Message(const unsigned char *msg, int msglen) : mymsg(msg, msglen) {
mymsg[0] = mymsg.length(); appendChecksum(); };
const unsigned char *getData() const { return mymsg.c_str(); }
size_t getLen() const { return mymsg.length(); }
private:
int appendChecksum();
std::basic_string<unsigned char> mymsg;
};
int Message::appendChecksum()
{
int sum = -std::accumulate(mymsg.begin(), mymsg.end(), 0);
mymsg.push_back(0xff & (sum >> 8));
mymsg.push_back(0xff & sum);
return sum;
}
现在在main例程中，您可以删除几十行代码并使用它们（如果您使用的是C ++ 11）：
Message setparams{{0x00, 0xc6, 0x04, 0x08, 0x11, 0xee, 0x01}};
Message beep{{0x00, 0xe6, 0x04, 0x00, 0x05}};
Message getrevision{{0x00, 0xA3, 0x04, 0x00}};
Message ledOn{{0x00, 0xe7, 0x04, 0x00, 0x0d, 0x00}};
如果您不使用C ++ 11（这将是一种耻辱！），您可以使用这种稍微不那么干净的风格：
unsigned char parms[] = {0x00, 0xc6, 0x04, 0x08, 0x11, 0xee, 0x01};
Message setparams(parms,sizeof(parms)/sizeof(parms[0]));
请注意，第一个字节设置为零而不是长度。这样做是因为构造函数在计算和附加校验和之前自动计算并设置该字节中的正确长度。当然，还有其他方法可以做到这一点，但我会把它留给你。
最后，通过循环，您现在可以使用此行：
int sizeSent = dev_rs232.sendDataBuffer(beep.getData(), beep.getLen());
实际上可能会或可能不会解决问题，但它会帮助您开始使用更清洁的程序。
此外，还有一些风格和设计建议：
using namespace std iostream代替printf setDefaultAttributes()，让构造函数设置正常的默认值static const的名称。它将使程序更易于理解和维护。boost::asio，而不是滚动自己的 修改：基于您敏锐（并且正确！）观察Message构造函数在投放普通unsigned char *时无法正常工作，我＆＃39 ; ve添加了第二个构造函数并修改了非C ++ 11版本的代码。很抱歉给您带来不便，感谢您保持诚实。
答案 1 :(得分：2)
/**
* Receive responses from the decoder
*/
int DeviceRS232::receiveDecodedData(unsigned char *dataBuffer, size_t bufferSize)
{
unsigned char recvBuffer[251];
unsigned char *ptrChar;
int nBytes, portStatus;
int inputBufSize = 0;
ChangeCTS(fdRS232, 0);
ChangeRTS(fdRS232, 0);
while(inputBufSize <= 0)
{
ioctl(fdRS232, FIONREAD, &inputBufSize);
usleep(1);
}
if(inputBufSize > 0)
{
int decodePacketLen = 0;
//unsigned char
memset(recvBuffer, 0x00, sizeof(recvBuffer));
nBytes = 0;
//usleep(100000);
while(nBytes < ((int)recvBuffer[0] + 2))
{
int index = 0;
int recvDataLen = 0;
if(nBytes != 0)
index = nBytes - 1;
recvDataLen = read(fdRS232, &recvBuffer[index], 251);
if(recvDataLen < 0)
{
std::cout << "[INFO@DeviceRS232::receiveDecodedData]File read error: " << strerror(errno) << std::endl;
//sleep(1);
}
nBytes += recvDataLen;
if(nBytes == ((int)recvBuffer[0] + 2))
break;
}
if(recvBuffer[1] == DECODE_DATA)
sendCommandToDecoder(OPCODE_ACK);
std::cout << "[INFO @ DeviceRS232::receiveDecodedData]Data Lenght (without CheckSum) : " << (int)recvBuffer[0] << std::endl;
for(int i=0; i<nBytes; i++)
{
std::cout << "recvBuffer[" << i << "]: ";
printf("%x\n", recvBuffer[i]);
}
std::cout << "-----------------------------------" << std::endl;
ChangeRTS(fdRS232, 1);
ChangeCTS(fdRS232, 1);
//sleep(1);
}
//strcpy((char *)dataBuffer, (char *)recvBuffer);
memcpy((char *)dataBuffer, recvBuffer, sizeof(recvBuffer)/sizeof(recvBuffer[0]));
inputBufSize = 0;
return nBytes;
}
/**
* Send commands to the decoder.
*/
int DeviceRS232::sendCommandToDecoder(unsigned int opCode)
{
unsigned char *commandBuffer;
int commandLength;
switch(opCode)
{
case OPCODE_ACK:
{
unsigned char ackString[] = {0x00, 0xD0, 0x04, 0x00};
commandLength = sizeof(ackString);
commandBuffer = ackString;
}
break;
case OPCODE_PARAM_SEND:
{
unsigned char paramSendString[] = {0x00, 0xC6, 0x04, 0x08, 0x00, 0xEE, 0x01};
commandLength = sizeof(paramSendString);
commandBuffer = paramSendString;
}
break;
default:
break;
}
Message msgCommand(commandBuffer, commandLength);
return sendDataBuffer(msgCommand.getCommandData(), msgCommand.getLen());
}
DeviceRS232.h头文件中定义的必需常量。