modbus_new_tcp_pi(3)

1MODBUS_NEW_TCP_PI(3)           libmodbus Manual           MODBUS_NEW_TCP_PI(3)
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NAME

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

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

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

41           modbus_t *ctx;
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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           }
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49           if (modbus_connect(ctx) == -1) {
50               fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
51               modbus_free(ctx);
52               return -1;
53           }
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AUTHORS

59       The libmodbus documentation was written by Stéphane Raimbault
60       <stephane.raimbault@gmail.com>
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64libmodbus v3.1.7                  07/20/2023              MODBUS_NEW_TCP_PI(3)