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.
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20       The service argument is the service name/port number to connect to. To
21       use the default Modbus port use the string "502". On many Unix systems,
22       it’s convenient to use a port number greater than or equal to 1024
23       because it’s not necessary to have administrator privileges.
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RETURN VALUE

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

31       EINVAL
32           The node string is empty or has been truncated. The service string
33           is empty or has been truncated.
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EXAMPLE

36           modbus_t *ctx;
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38           ctx = modbus_new_tcp_pi("::1", "1502");
39           if (ctx == NULL) {
40               fprintf(stderr, "Unable to allocate libmodbus context\n");
41               return -1;
42           }
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44           if (modbus_connect(ctx) == -1) {
45               fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
46               modbus_free(ctx);
47               return -1;
48           }
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AUTHORS

54       The libmodbus documentation was written by Stéphane Raimbault
55       <stephane.raimbault@gmail.com[1]>
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NOTES

58        1. stephane.raimbault@gmail.com
59           mailto:stephane.raimbault@gmail.com
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63libmodbus 3.0.6                   04/02/2014              MODBUS_NEW_TCP_PI(3)