Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
MODBUS_NEW_TCP(3)	       libmodbus Manual		     MODBUS_NEW_TCP(3)

NAME
       modbus_new_tcp -	create a libmodbus context for TCP/IPv4

SYNOPSIS
       modbus_t	*modbus_new_tcp(const char *ip,	int port);

DESCRIPTION
       The modbus_new_tcp() function shall allocate and	initialize a modbus_t
       structure to communicate	with a Modbus TCP IPv4 server.

       The ip argument specifies the IP	address	of the server to which the
       client wants to establish a connection. A NULL value can	be used	to
       listen any addresses in server mode.

       The port	argument is the	TCP port to use. Set the port to
       MODBUS_TCP_DEFAULT_PORT to use the default one (502). It's convenient
       to use a	port number greater than or equal to 1024 because it's not
       necessary to have administrator privileges.

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
       EINVAL
	   An invalid IP address was given.

EXAMPLE
	   modbus_t *ctx;

	   ctx = modbus_new_tcp("127.0.0.1", 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
       modbus_tcp_listen(3) modbus_free(3)

AUTHORS
       The libmodbus documentation was written by StA(C)phane Raimbault
       <stephane.raimbault@gmail.com>

libmodbus v3.1.4		  04/29/2017		     MODBUS_NEW_TCP(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLE | SEE ALSO | AUTHORS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=modbus_new_tcp&sektion=3&manpath=FreeBSD+12.0-RELEASE+and+Ports>

home | help