Linux写串口到C++返回坏文件描述符 >我正在编写一个C++程序，从位于/DEV/TTACACM0的设备发送接收数据。我可以从设备中读取，没有问题，我可以从命令行写入它，但是我不能在我的C++程序中写入它。以下是我到目前为止的情况： #include "SerialComms.h" #include <errno.h> #include <string.h> SerialComms::SerialComms() { serial_filestream = -1; //CONFIGURE THE PORT //The flags (defined in /usr/include/termios.h - see http://pubs.opengroup.org/onlinepubs/007908799/xsh/termios.h.html): // Baud rate:- B1200, B2400, B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800, B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000, B2500000, B3000000, B3500000, B4000000 // CSIZE:- CS5, CS6, CS7, CS8 // CLOCAL - Ignore modem status lines // CREAD - Enable receiver // IGNPAR = Ignore characters with parity errors // ICRNL - Map CR to NL on input // PARENB - Parity enable // PARODD - Odd parity (else even) tcgetattr(serial_filestream, &options); options.c_cflag = B9600 | CS8 | CLOCAL | CREAD; //<Set baud rate options.c_iflag = IGNPAR; options.c_oflag = 0; options.c_lflag = 0; } bool SerialComms::Init(string type){ //The flags (defined in fcntl.h): // Access modes (use 1 of these): // O_RDONLY - Open for reading only. // O_RDWR - Open for reading and writing. // O_WRONLY - Open for writing only. // // O_NDELAY / O_NONBLOCK (same function) - Enables nonblocking mode. When set read requests on the file can return immediately with a failure status // if there is no input immediately available (instead of blocking). Likewise, write requests can also return // immediately with a failure status if the output can't be written immediately. // // O_NOCTTY - When set and path identifies a terminal device, open() shall not cause the terminal device to become the controlling terminal for the process. if (type == "USB"){ //if type equals USB, open USB serial_filestream = open(USBSerial, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode }else if (type == "UART1"){ serial_filestream = open(UART1, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode } if (serial_filestream == -1) { //ERROR - CAN'T OPEN SERIAL PORT printf("Error - Unable to open: %s\n", type.c_str()); }else{ printf("Opened serial type: %s\n", type.c_str()); } tcflush(serial_filestream, TCIFLUSH); tcsetattr(serial_filestream, TCSANOW, &options); printf("Serial Comms for type: %s intialized", type.c_str()); return 1; } bool SerialComms::Ping(){ WriteSerial("p,1,1;\n"); return true; } char* SerialComms::ReadSerial(){ if (serial_filestream != -1) { // Read up to 255 characters from the port if they are there char rx_buffer[256]; int rx_length = read(serial_filestream, (void*)rx_buffer, 255); //Filestream, buffer to store in, number of bytes to read (max) if (rx_length < 0) { //An error occured (will occur if there are no bytes) } else if (rx_length == 0) { //No data waiting } else { //Bytes received rx_buffer[rx_length] = '\0'; int j = 0; while (rx_buffer[j] != ';' && rx_buffer[j] != '\0' && rx_buffer[j] != '\n'){ j++; } char rx_return[j+1]; for(int i = 0; i < j+1; i++){ rx_return[i] = rx_buffer[i]; } rx_return[j+1] = '\0'; return rx_return; } } return '\0'; } bool SerialComms::WriteSerial(string data_out){ const char * tx_buffer = data_out.c_str(); if (serial_filestream != -1) { int wr = write(serial_filestream, tx_buffer, strlen(tx_buffer)); if (wr < 0){ printf("Error writing to Serial: %s \n", strerror(errno)); return 0; } else{ printf("WroteSerial: %s, %d \n", tx_buffer, strlen(tx_buffer)); return 1; } }else{ printf("Error writing to Serial filestream errors \n"); return 0; } return 1; } SerialComms::~SerialComms() { close(serial_filestream); }_C++_Linux_Serial Port

cplusplus/
Linux写串口到C++返回坏文件描述符 >我正在编写一个C++程序，从位于/DEV/TTACACM0的设备发送接收数据。我可以从设备中读取，没有问题，我可以从命令行写入它，但是我不能在我的C++程序中写入它。以下是我到目前为止的情况： #include "SerialComms.h" #include <errno.h> #include <string.h> SerialComms::SerialComms() { serial_filestream = -1; //CONFIGURE THE PORT //The flags (defined in /usr/include/termios.h - see http://pubs.opengroup.org/onlinepubs/007908799/xsh/termios.h.html): // Baud rate:- B1200, B2400, B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800, B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000, B2500000, B3000000, B3500000, B4000000 // CSIZE:- CS5, CS6, CS7, CS8 // CLOCAL - Ignore modem status lines // CREAD - Enable receiver // IGNPAR = Ignore characters with parity errors // ICRNL - Map CR to NL on input // PARENB - Parity enable // PARODD - Odd parity (else even) tcgetattr(serial_filestream, &options); options.c_cflag = B9600 | CS8 | CLOCAL | CREAD; //<Set baud rate options.c_iflag = IGNPAR; options.c_oflag = 0; options.c_lflag = 0; } bool SerialComms::Init(string type){ //The flags (defined in fcntl.h): // Access modes (use 1 of these): // O_RDONLY - Open for reading only. // O_RDWR - Open for reading and writing. // O_WRONLY - Open for writing only. // // O_NDELAY / O_NONBLOCK (same function) - Enables nonblocking mode. When set read requests on the file can return immediately with a failure status // if there is no input immediately available (instead of blocking). Likewise, write requests can also return // immediately with a failure status if the output can't be written immediately. // // O_NOCTTY - When set and path identifies a terminal device, open() shall not cause the terminal device to become the controlling terminal for the process. if (type == "USB"){ //if type equals USB, open USB serial_filestream = open(USBSerial, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode }else if (type == "UART1"){ serial_filestream = open(UART1, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode } if (serial_filestream == -1) { //ERROR - CAN'T OPEN SERIAL PORT printf("Error - Unable to open: %s\n", type.c_str()); }else{ printf("Opened serial type: %s\n", type.c_str()); } tcflush(serial_filestream, TCIFLUSH); tcsetattr(serial_filestream, TCSANOW, &options); printf("Serial Comms for type: %s intialized", type.c_str()); return 1; } bool SerialComms::Ping(){ WriteSerial("p,1,1;\n"); return true; } char* SerialComms::ReadSerial(){ if (serial_filestream != -1) { // Read up to 255 characters from the port if they are there char rx_buffer[256]; int rx_length = read(serial_filestream, (void*)rx_buffer, 255); //Filestream, buffer to store in, number of bytes to read (max) if (rx_length < 0) { //An error occured (will occur if there are no bytes) } else if (rx_length == 0) { //No data waiting } else { //Bytes received rx_buffer[rx_length] = '\0'; int j = 0; while (rx_buffer[j] != ';' && rx_buffer[j] != '\0' && rx_buffer[j] != '\n'){ j++; } char rx_return[j+1]; for(int i = 0; i < j+1; i++){ rx_return[i] = rx_buffer[i]; } rx_return[j+1] = '\0'; return rx_return; } } return '\0'; } bool SerialComms::WriteSerial(string data_out){ const char * tx_buffer = data_out.c_str(); if (serial_filestream != -1) { int wr = write(serial_filestream, tx_buffer, strlen(tx_buffer)); if (wr < 0){ printf("Error writing to Serial: %s \n", strerror(errno)); return 0; } else{ printf("WroteSerial: %s, %d \n", tx_buffer, strlen(tx_buffer)); return 1; } }else{ printf("Error writing to Serial filestream errors \n"); return 0; } return 1; } SerialComms::~SerialComms() { close(serial_filestream); }

Linux写串口到C++返回坏文件描述符 >我正在编写一个C++程序，从位于/DEV/TTACACM0的设备发送接收数据。我可以从设备中读取，没有问题，我可以从命令行写入它，但是我不能在我的C++程序中写入它。以下是我到目前为止的情况： #include "SerialComms.h" #include <errno.h> #include <string.h> SerialComms::SerialComms() { serial_filestream = -1; //CONFIGURE THE PORT //The flags (defined in /usr/include/termios.h - see http://pubs.opengroup.org/onlinepubs/007908799/xsh/termios.h.html): // Baud rate:- B1200, B2400, B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800, B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000, B2500000, B3000000, B3500000, B4000000 // CSIZE:- CS5, CS6, CS7, CS8 // CLOCAL - Ignore modem status lines // CREAD - Enable receiver // IGNPAR = Ignore characters with parity errors // ICRNL - Map CR to NL on input // PARENB - Parity enable // PARODD - Odd parity (else even) tcgetattr(serial_filestream, &options); options.c_cflag = B9600 | CS8 | CLOCAL | CREAD; //<Set baud rate options.c_iflag = IGNPAR; options.c_oflag = 0; options.c_lflag = 0; } bool SerialComms::Init(string type){ //The flags (defined in fcntl.h): // Access modes (use 1 of these): // O_RDONLY - Open for reading only. // O_RDWR - Open for reading and writing. // O_WRONLY - Open for writing only. // // O_NDELAY / O_NONBLOCK (same function) - Enables nonblocking mode. When set read requests on the file can return immediately with a failure status // if there is no input immediately available (instead of blocking). Likewise, write requests can also return // immediately with a failure status if the output can't be written immediately. // // O_NOCTTY - When set and path identifies a terminal device, open() shall not cause the terminal device to become the controlling terminal for the process. if (type == "USB"){ //if type equals USB, open USB serial_filestream = open(USBSerial, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode }else if (type == "UART1"){ serial_filestream = open(UART1, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode } if (serial_filestream == -1) { //ERROR - CAN'T OPEN SERIAL PORT printf("Error - Unable to open: %s\n", type.c_str()); }else{ printf("Opened serial type: %s\n", type.c_str()); } tcflush(serial_filestream, TCIFLUSH); tcsetattr(serial_filestream, TCSANOW, &options); printf("Serial Comms for type: %s intialized", type.c_str()); return 1; } bool SerialComms::Ping(){ WriteSerial("p,1,1;\n"); return true; } char* SerialComms::ReadSerial(){ if (serial_filestream != -1) { // Read up to 255 characters from the port if they are there char rx_buffer[256]; int rx_length = read(serial_filestream, (void*)rx_buffer, 255); //Filestream, buffer to store in, number of bytes to read (max) if (rx_length < 0) { //An error occured (will occur if there are no bytes) } else if (rx_length == 0) { //No data waiting } else { //Bytes received rx_buffer[rx_length] = '\0'; int j = 0; while (rx_buffer[j] != ';' && rx_buffer[j] != '\0' && rx_buffer[j] != '\n'){ j++; } char rx_return[j+1]; for(int i = 0; i < j+1; i++){ rx_return[i] = rx_buffer[i]; } rx_return[j+1] = '\0'; return rx_return; } } return '\0'; } bool SerialComms::WriteSerial(string data_out){ const char * tx_buffer = data_out.c_str(); if (serial_filestream != -1) { int wr = write(serial_filestream, tx_buffer, strlen(tx_buffer)); if (wr < 0){ printf("Error writing to Serial: %s \n", strerror(errno)); return 0; } else{ printf("WroteSerial: %s, %d \n", tx_buffer, strlen(tx_buffer)); return 1; } }else{ printf("Error writing to Serial filestream errors \n"); return 0; } return 1; } SerialComms::~SerialComms() { close(serial_filestream); }

c++ linux serial-port

Linux写串口到C++返回坏文件描述符 >我正在编写一个C++程序，从位于/DEV/TTACACM0的设备发送接收数据。我可以从设备中读取，没有问题，我可以从命令行写入它，但是我不能在我的C++程序中写入它。以下是我到目前为止的情况： #include "SerialComms.h" #include <errno.h> #include <string.h> SerialComms::SerialComms() { serial_filestream = -1; //CONFIGURE THE PORT //The flags (defined in /usr/include/termios.h - see http://pubs.opengroup.org/onlinepubs/007908799/xsh/termios.h.html): // Baud rate:- B1200, B2400, B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800, B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000, B2500000, B3000000, B3500000, B4000000 // CSIZE:- CS5, CS6, CS7, CS8 // CLOCAL - Ignore modem status lines // CREAD - Enable receiver // IGNPAR = Ignore characters with parity errors // ICRNL - Map CR to NL on input // PARENB - Parity enable // PARODD - Odd parity (else even) tcgetattr(serial_filestream, &options); options.c_cflag = B9600 | CS8 | CLOCAL | CREAD; //<Set baud rate options.c_iflag = IGNPAR; options.c_oflag = 0; options.c_lflag = 0; } bool SerialComms::Init(string type){ //The flags (defined in fcntl.h): // Access modes (use 1 of these): // O_RDONLY - Open for reading only. // O_RDWR - Open for reading and writing. // O_WRONLY - Open for writing only. // // O_NDELAY / O_NONBLOCK (same function) - Enables nonblocking mode. When set read requests on the file can return immediately with a failure status // if there is no input immediately available (instead of blocking). Likewise, write requests can also return // immediately with a failure status if the output can't be written immediately. // // O_NOCTTY - When set and path identifies a terminal device, open() shall not cause the terminal device to become the controlling terminal for the process. if (type == "USB"){ //if type equals USB, open USB serial_filestream = open(USBSerial, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode }else if (type == "UART1"){ serial_filestream = open(UART1, O_RDWR | O_NOCTTY | O_NDELAY); //Open in non blocking read/write mode } if (serial_filestream == -1) { //ERROR - CAN'T OPEN SERIAL PORT printf("Error - Unable to open: %s\n", type.c_str()); }else{ printf("Opened serial type: %s\n", type.c_str()); } tcflush(serial_filestream, TCIFLUSH); tcsetattr(serial_filestream, TCSANOW, &options); printf("Serial Comms for type: %s intialized", type.c_str()); return 1; } bool SerialComms::Ping(){ WriteSerial("p,1,1;\n"); return true; } char* SerialComms::ReadSerial(){ if (serial_filestream != -1) { // Read up to 255 characters from the port if they are there char rx_buffer[256]; int rx_length = read(serial_filestream, (void*)rx_buffer, 255); //Filestream, buffer to store in, number of bytes to read (max) if (rx_length < 0) { //An error occured (will occur if there are no bytes) } else if (rx_length == 0) { //No data waiting } else { //Bytes received rx_buffer[rx_length] = '\0'; int j = 0; while (rx_buffer[j] != ';' && rx_buffer[j] != '\0' && rx_buffer[j] != '\n'){ j++; } char rx_return[j+1]; for(int i = 0; i < j+1; i++){ rx_return[i] = rx_buffer[i]; } rx_return[j+1] = '\0'; return rx_return; } } return '\0'; } bool SerialComms::WriteSerial(string data_out){ const char * tx_buffer = data_out.c_str(); if (serial_filestream != -1) { int wr = write(serial_filestream, tx_buffer, strlen(tx_buffer)); if (wr < 0){ printf("Error writing to Serial: %s \n", strerror(errno)); return 0; } else{ printf("WroteSerial: %s, %d \n", tx_buffer, strlen(tx_buffer)); return 1; } }else{ printf("Error writing to Serial filestream errors \n"); return 0; } return 1; } SerialComms::~SerialComms() { close(serial_filestream); },c++,linux,serial-port,C++,Linux,Serial Port,它工作正常，我从串行设备接收到预期的数据但是，C++程序中的主循环调用一次写函数，例如： void Ping(SerialComms serialLine){ serialLine.WriteSerial("p,1,1;\n"); printf("pinged at: %s \n", ctime(&now)); } 第一次执行写入时，不会给出错误，但似乎不起作用，第二次写入返回错误的文件描述符错误。此外，它也会使端口的读数出错。这是我的程序输出： WroteSeria

它工作正常，我从串行设备接收到预期的数据

但是，C++程序中的主循环调用一次写函数，例如：

void Ping(SerialComms serialLine){
    serialLine.WriteSerial("p,1,1;\n");
    printf("pinged at: %s \n", ctime(&now));
}

第一次执行写入时，不会给出错误，但似乎不起作用，第二次写入返回错误的文件描述符错误。此外，它也会使端口的读数出错。这是我的程序输出：

WroteSerial: p,1,1;
, 7 
pinged at: Wed Dec 30 19:08:05 2015

Error writing to Serial: Bad file descriptor 
pinged at: Wed Dec 30 19:09:06 2015

我真的不知道从这里去哪里，所以任何建议都将不胜感激。我很确定我错过了一些基本的东西，但我现在看不到

我在这里看到一个常见的错误，即假设如果调用write来写入10个字节，那么write将写入10个字节。事实并非如此。请参阅write的手册页。write可能决定此时只能写入5个字节，并返回5个字节。尤其是因为你用的是O_ndeley！在写入设备文件描述符时，尤其是使用O_NDELAY时，在写入之前，必须始终使用poll或select等待文件描述符可写入。然后，检查是否已写入所有字节，如果未写入，则必须重复轮询/选择，然后尝试写入其余字节。P.S。从O_____________________________________________________。通过为垃圾-1文件描述符调用termios结构，您可能会在termios结构中获得奇怪的值，然后在调用tcsetattr时可能会弄乱真正的文件描述符。我唯一的另一个建议是，在调用tcsetattr之前，尝试在termios结构上调用cfmakeraw-有时这可以解决串行设备的神秘错误。在消息Error writing to serial:…和WroteSerial:…中打印串行文件流，以检查它是否被覆盖，或者使用strace-ewrite…。

WroteSerial: p,1,1;
, 7 
pinged at: Wed Dec 30 19:08:05 2015

Error writing to Serial: Bad file descriptor 
pinged at: Wed Dec 30 19:09:06 2015

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