Modbus

libmodbus驱动可以同时应用在多个串口上面吗

发布于 2020-09-08 11:32:32 浏览：2228 订阅该版

文武斌 2020-09-08

这家伙很懒，什么也没写！

晨起小酌 2020-09-08

这家伙很懒，什么也没写！

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4 个回答

晨起小酌 2020-09-08

这家伙很懒，什么也没写！

```c
modbus_t* modbus_new_rtu(const char *device,
                         int baud, char parity, int data_bit,
                         int stop_bit)
{
    modbus_t *ctx;
    modbus_rtu_t *ctx_rtu;

/* Check device argument */
    if (device == NULL || *device == 0) {
        fprintf(stderr, "The device string is empty\n");
        errno = EINVAL;
        return NULL;
    }

/* Check baud argument */
    if (baud == 0) {
        fprintf(stderr, "The baud rate value must not be zero\n");
        errno = EINVAL;
        return NULL;
    }

ctx = (modbus_t *)malloc(sizeof(modbus_t));
    _modbus_init_common(ctx);
    ctx->backend = &_modbus_rtu_backend;
    ctx->backend_data = (modbus_rtu_t *)malloc(sizeof(modbus_rtu_t));
    ctx_rtu = (modbus_rtu_t *)ctx->backend_data;
    ctx_rtu->device = NULL;

/* Device name and \0 */
    ctx_rtu->device = (char *)malloc((strlen(device) + 1) * sizeof(char));
    strcpy(ctx_rtu->device, device);

ctx_rtu->baud = baud;
    if (parity == 'N' || parity == 'E' || parity == 'O') {
        ctx_rtu->parity = parity;
    } else {
        modbus_free(ctx);
        errno = EINVAL;
        return NULL;
    }
    ctx_rtu->data_bit = data_bit;
    ctx_rtu->stop_bit = stop_bit;

#if HAVE_DECL_TIOCSRS485
    /* The RS232 mode has been set by default */
    ctx_rtu->serial_mode = MODBUS_RTU_RS232;
#endif

#if HAVE_DECL_TIOCM_RTS
    /* The RTS use has been set by default */
    ctx_rtu->rts = MODBUS_RTU_RTS_NONE;

/* Calculate estimated time in micro second to send one byte */
    ctx_rtu->onebyte_time = 1000000 * (1 + data_bit + (parity == 'N' ? 0 : 1) + stop_bit) / baud;
    
    ctx_rtu->rts_pin = 0;
    
    /* The internal function is used by default to set RTS */
    ctx_rtu->set_rts = _modbus_rtu_ioctl_rts;

/* The delay before and after transmission when toggling the RTS pin */
    ctx_rtu->rts_delay = ctx_rtu->onebyte_time;
#endif

ctx_rtu->confirmation_to_ignore = FALSE;

return ctx;
}
```