modbus_new_tcp_pi(3)

1MODBUS_NEW_TCP_PI(3)           libmodbus Manual           MODBUS_NEW_TCP_PI(3)
2
3
4

NAME

6       modbus_new_tcp_pi - create a libmodbus context for TCP Protocol
7       Independent
8

SYNOPSIS

10       modbus_t *modbus_new_tcp_pi(const char *node, const char *service);
11

DESCRIPTION

13       The modbus_new_tcp_pi() function shall allocate and initialize a
14       modbus_t structure to communicate with a Modbus TCP IPv4 or IPv6
15       server.
16
17       The node argument specifies the host name or IP address of the host to
18       connect to, eg. "192.168.0.5" , "::1" or "server.com". A NULL value can
19       be used to listen any addresses in server mode.
20
21       The service argument is the service name/port number to connect to. To
22       use the default Modbus port use the string "502". On many Unix systems,
23       it’s convenient to use a port number greater than or equal to 1024
24       because it’s not necessary to have administrator privileges.
25

RETURN VALUE

27       The function shall return a pointer to a modbus_t structure if
28       successful. Otherwise it shall return NULL and set errno to one of the
29       values defined below.
30

ERRORS

32       EINVAL
33           The node string is empty or has been truncated. The service string
34           is empty or has been truncated.
35
36       ENOMEM
37           Out of memory. Possibly, the application hits its memory limit
38           and/or whole system is running out of memory.
39

EXAMPLE

41           modbus_t *ctx;
42
43           ctx = modbus_new_tcp_pi("::1", "1502");
44           if (ctx == NULL) {
45               fprintf(stderr, "Unable to allocate libmodbus context\n");
46               return -1;
47           }
48
49           if (modbus_connect(ctx) == -1) {
50               fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
51               modbus_free(ctx);
52               return -1;
53           }
54

AUTHORS

59       The libmodbus documentation was written by Stéphane Raimbault
60       <stephane.raimbault@gmail.com>
61
62
63
64libmodbus v3.1.6                  07/21/2022              MODBUS_NEW_TCP_PI(3)