Name

modbus_new_tcp_pi - create a libmodbus context for TCP Protocol Independent

Synopsis

*modbus_t *modbus_new_tcp_pi(const char *node, const char *service);

Description

The modbus_new_tcp_pi() function shall allocate and initialize a modbus_t structure to communicate with a Modbus TCP IPv4 or IPv6 server.

The node argument specifies the host name or IP address of the host to connect to, eg. "192.168.0.5" , "::1" or "server.com". A NULL value can be used to listen any addresses in server mode.

because it’s not necessary to have administrator privileges.

because it’s not necessary to have administrator privileges.

because it’s not necessary to have administrator privileges.

because it’s not necessary to have administrator privileges.

?s not necessary to have administrator privileges.

:octicons-tag-24: v3.1.8 handles NULL value for service (no EINVAL error).

Return value

The function shall return a pointer to a modbus_t structure if successful. Otherwise it shall return NULL and set errno to one of the values defined below.

Errors

Example

modbus_t *ctx;
ctx = modbus_new_tcp_pi("::1", "1502");
if (ctx == NULL) {


    fprintf(stderr, "Unable to allocate libmodbus context\n");


    return -1;
}
if (modbus_connect(ctx) == -1) {


    fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));


    modbus_free(ctx);


    return -1;
}

See also