cannot have ModbusRTU (serial) working in linux

[arkypita]

Hi, I tried the example with ModbusTCP and it works perfectly
I also need to use serial port, but I am not able to get the library to work properly in ModbusRTU mode with Linux (timeout, sometime read sometime not, read 1 address ok, read 2 addresses fail get timeout etc)

I can't find an example for the serial in Linux, do you have one?

[arkypita]

Actually my best implementation look like this.
It works well if I read ONE register but fails when I read two or more register (return NMBS_ERROR_TIMEOUT).

void * connect_rtu(char * port, int speed, char parity, int data_bits, int stop_bits)
{
    printf("Opening serial port... ");

    int fd = open(port, O_RDWR | O_NOCTTY | O_SYNC);

    if (fd < 0) {
        printf("Error!\n");
        return 1;
    }

    struct termios tty;
    if (tcgetattr(fd, &tty) != 0) {
        printf("Error getting terminal attributes!\n");
        close(fd);
        return 1;
    }

    // Configure port
    cfsetospeed(&tty, speed); // Set output baud rate
    cfsetispeed(&tty, speed); // Set input baud rate

    tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS8; // 8 data bits
    tty.c_cflag &= ~PARENB;                    // No parity
    tty.c_cflag &= ~CSTOPB;                    // 1 stop bit
    tty.c_cflag |= (CLOCAL | CREAD);           // Local line | Enable receiver

    tty.c_iflag &= ~IGNBRK; // Disable break processing
    tty.c_lflag = 0;        // No signaling chars, no echo, no canonical processing
    tty.c_oflag = 0;        // No remapping, no delays
    tty.c_cc[VMIN] = 1;     // Read at least 1 character
    tty.c_cc[VTIME] = 1;    // Wait for up to 0.1s

    if (tcsetattr(fd, TCSANOW, &tty) != 0) {
        printf("Error setting terminal attributes!\n");
        close(fd);
        return NULL;
    }

    printf("Success!\n");

    client_connection = fd;
    return &client_connection;
}

int32_t read_fd_linux(uint8_t* buf, uint16_t count, int32_t timeout_ms, void* arg) 
{

    if (!arg) return -1;
    int fd = *(int*) arg;

    struct pollfd pfd = {
        .fd = fd,
        .events = POLLIN // Wait for data to read
    };

    int poll_result = poll(&pfd, 1, timeout_ms);
    if (poll_result < 0) {
        return -1; // Error during poll
    } else if (poll_result == 0) {
        return 0; // Timeout occurred
    }

    if (pfd.revents & POLLIN) {
        ssize_t bytes_read = read(fd, buf, count);
        if (bytes_read < 0) {
            return -1; // Error during read
        }
        return (int32_t)bytes_read;
    }

    return -1; // Unexpected condition

}

int32_t write_fd_linux(const uint8_t* buf, uint16_t count, int32_t timeout_ms, void* arg) 
{

    if (!arg) return -1;
    int fd = *(int*) arg;

#if (TRANSPORT_MODE == MODE_RTU)

    struct pollfd pfd = {
        .fd = fd,
        .events = POLLOUT // Wait for the ability to write
    };

    int poll_result = poll(&pfd, 1, timeout_ms);
    if (poll_result < 0) {
        return -1; // Error during poll
    } else if (poll_result == 0) {
        return 0; // Timeout occurred
    }

    if (pfd.revents & POLLOUT) {
        ssize_t bytes_written = write(fd, buf, count);
        if (bytes_written < 0) {
            return -1; // Error during write
        }
        return (int32_t)bytes_written;
    }

    return -1; // Unexpected condition
}

[arkypita]

What I also try is to use the same read/write implementation as in client-tcp, but i have the same issue