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.

The service argument is the service name/port number to connect to. To use the default Modbus port use the string "502". On many Unix systems, it\(cqs convenient to use a port number greater than or equal to 1024 because it\(cqs not necessary to have administrator privileges.

RETURN VALUE

The modbus_new_tcp_pi() 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

EINVAL

The node string is empty or has been truncated. The service string is empty or has been truncated.

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;
}

RELATED TO modbus_new_tcp_pi…

modbus_new_tcp(3) modbus_new_rtu(3) modbus_free(3)

AUTHORS

The libmodbus documentation was written by St\('ephane Raimbault <\m[blue][email protected]\m[]\s-2\u[1]\d\s+2>

NOTES

1.

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modbus_new_tcp_pi (3)