modbus_new_tcp(3)

1MODBUS_NEW_TCP(3)              Libmodbus Manual              MODBUS_NEW_TCP(3)
2
3
4

NAME

6       modbus_new_tcp - create a libmodbus context for TCP/IPv4
7

SYNOPSIS

9       modbus_t *modbus_new_tcp(const char *ip, int port);
10

DESCRIPTION

12       The modbus_new_tcp() function shall allocate and initialize a modbus_t
13       structure to communicate with a Modbus TCP/IPv4 server.
14
15       The ip argument specifies the IP address of the server to which the
16       client wants etablish a connection.
17
18       The port argument is the TCP port to use. Set the port to
19       MODBUS_TCP_DEFAULT_PORT to use the default one (502). It’s convenient
20       to use a port number greater than or equal to 1024 because it’s not
21       necessary to have administrator privileges.
22

RETURN VALUE

24       The modbus_new_tcp() function shall return a pointer to a modbus_t
25       structure if successful. Otherwise it shall return NULL and set errno
26       to one of the values defined below.
27

ERRORS

29       EINVAL
30           An invalid IP address was given.
31

EXAMPLE

33           modbus_t *ctx;
34
35           ctx = modbus_new_tcp("127.0.0.1", 1502);
36           if (ctx == NULL) {
37               fprintf(stderr, "Unable to allocate libmodbus context\n");
38               return -1;
39           }
40
41           if (modbus_connect(ctx) == -1) {
42               fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
43               modbus_free(ctx);
44               return -1;
45           }
46

AUTHORS

51       The libmodbus documentation was written by Stéphane Raimbault
52       <stephane.raimbault@gmail.com[1]>
53

NOTES

55        1. stephane.raimbault@gmail.com
56           mailto:stephane.raimbault@gmail.com
57
58
59
60libmodbus 3.0.8                   07/31/2019                 MODBUS_NEW_TCP(3)