modbus_new_rtu(3)

1MODBUS_NEW_RTU(3)              Libmodbus Manual              MODBUS_NEW_RTU(3)
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NAME

6       modbus_new_rtu - create a libmodbus context for RTU
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SYNOPSIS

9       modbus_t *modbus_new_rtu(const char *device, int baud, char parity, int
10       data_bit, int stop_bit);
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DESCRIPTION

13       The modbus_new_rtu() function shall allocate and initialize a modbus_t
14       structure to communicate in RTU mode on a serial line.
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16       The device argument specifies the name of the serial port handled by
17       the OS, eg. /dev/ttyS0 or /dev/ttyUSB0. On Windows, it’s necessary to
18       prepend COM name with \\.\ for COM number greater than 9, eg.
19       \\\\.\\COM10. See
20       http://msdn.microsoft.com/en-us/library/aa365247(v=vs.85).aspx for
21       details
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23       The baud argument specifies the baud rate of the communication, eg.
24       9600, 19200, 57600, 115200, etc.
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26       The parity argument can have one of the following values
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28           ·   N for none
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30           ·   E for even
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32           ·   O for odd
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34       The data_bits argument specifies the number of bits of data, the
35       allowed values are 5, 6, 7 and 8.
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37       The stop_bits argument specifies the bits of stop, the allowed values
38       are 1 and 2.
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RETURN VALUE

41       The modbus_new_rtu() function shall return a pointer to a modbus_t
42       structure if successful. Otherwise it shall return NULL and set errno
43       to one of the values defined below.
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ERRORS

46       EINVAL
47           An invalid argument was given.
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EXAMPLE

50           modbus_t *ctx;
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52           ctx = modbus_new_rtu("/dev/ttyUSB0", 115200, 'N', 8, 1);
53           if (ctx == NULL) {
54               fprintf(stderr, "Unable to create the libmodbus context\n");
55               return -1;
56           }
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AUTHORS

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

66        1. stephane.raimbault@gmail.com
67           mailto:stephane.raimbault@gmail.com
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71libmodbus 3.0.8                   07/31/2019                 MODBUS_NEW_RTU(3)