Peter M. Groen / libmodbus

The arguments are surrounded by parentheses to be evaluated first.

The _modbus_receive_confirmation()_ function shall receive a
request via the socket of the context 'ctx'. This function must be
used for debugging purposes because the received response isn't
checked against the initial request. This function can be
convenient to receive request not handled by the library.

The _modbus_send_raw_request()_ function shall send a request via
the socket of the context 'ctx'. This function must be used for
debugging purposes because you have to take care to make a valid
request by hand. The function only adds to the message, the header
or CRC of the selected backend, so 'raw_req' must start and contain
at least a slave/unit identifier and a function code. This function
can be used to send request not handled by the library.

The error reported by #9 was already fixed in master but this change
scrupulously respects the definition of DWORD.

Each function is decribed in one txt file. The file libmodbus.txt
offers an overview of the library.

It's possible to generate HTML and man outputs from the txt file.
The documentation can be generated only if you have the required
tools (asciidoc and xmlto).

Better results are obtained with AsciiDoc v8.6+

- updated comments
- renamed internal constants (eg. _TIME_OUT_BEGIN_OF_TRAME in
  _TIME_OUT_BEGIN_OF_MESSAGE)

To avoid to duplicate the documentation between source and
documentation. The information already available in documentation
is removed from source.

Reported by Tobias Doerffel.

Reported by Allan Cornet.

- removed ENOTCONN errno not supported
- set WINVER to Windows XP (and above) and add ws2_32.dll. So older
  Windows versions aren't supported.

Reported by Patsy Kaye.
Removed useless asignment at the same time.

Inspired by the branch ff/ipv6 of Florian Forster but this version uses
a specific PI backend to isolate the IPv4 and IPv6 implementations.

The existing TCP/IPv4 implementation has been kept intact (not rebased
on the PI one) because its data backend requires fewer bytes than the PI.

New functions modbus_new_tcp_pi, modbus_tcp_pi_listen and
modbus_tcp_pi_accept and new backend called modbus_tcp_pi_t.

In modbus-tcp.c:
- Needed to include <signal.h>
- Added Jay's fix for __OpenBSD__
- SIGPIPE ignore handler needs to return a pointer instead of an integer.

Patch provided bu Barry Grumbine and Jason Oster.

Reported by Marco Sala.

Page 38 in the document Modbus_Application_Protocol_V1_1b.pdf:
6.17 23 (0x17) Read/Write Multiple registers

This function code performs a combination of one read operation
and one write operation in a single MODBUS transaction. The write
operation is performed before the read.

The unit test has been updated.

Original patch by Jason Oster

Win32 uses a specific function to close socket.
Reported by Petr Parýzek.

Reported by Antti Manninen and according to Page6 in the document
"MODBUS Messaging on TCP/IP Implementation Guide V1.0b",
------------------------
Unit Identifier – This field is used for intra-system routing purpose.
It is typically used to communicate to a MODBUS+ or a MODBUS serial
line slave through a gateway between an Ethernet TCP-IP network and
a MODBUS serial line. This field is set by the MODBUS Client in the
request and must be returned with the same value in the response by
the server.
------------------------

Contributed by Dominic Storey.
- new function modbus_reply_exception
- unit test

- MODBUS_GET_INT32_FROM_INT16
- MODBUS_GET_INT16_FROM_INT8
- MODBUS_SET_INT16_TO_INT8
- check the trame length before indexing in unit-test-server

- new public function
- change unit-test-server.c to be transport layer independant (query
  and header_length)

The goal of this rewriting is to avoid the timeouts on the receiving
of exceptions and to be more robust on bad requests. Some devices
use the exception MODBUS_EXCEPTION_ACKNOWLEDGE to response to some
valid requests, so in this case, you'll really appreciate this
change!

- Slower! More system calls are used.
- The code is cleaner and easier to understand.
- Really faster when an exception occurs.
- Fix unit test of bad request in RTU

Reported by Ivan Giuliani <giuliani.v@gmail.com>
It was not possible to use libmodbus outside of projects without
config.h file.

The inclusion has been removed from the public header.

Signed-off-by: Stéphane Raimbault <stephane.raimbault@gmail.com>

These functions have no meaning in RTU so it's better to specialize
the names and remove them from the backend.

- remove the functions from the backend
- update tests to handle RTU mode (master and slave)
- add command line options to tests (rtu or tcp)

- check strlcpy in configure.ac
- test for empty device string
- test truncated device string

When unitialized the socket can be 0 and write calls success.

modbus_set_slave must be used to set the slave ID of the remote
device to talk in master mode and to set the internal slave ID in
slave mode.

If you talk to several devices, you need to call modbus_set_slave
each time the following requests must be sent to another device.

- move termios header in RTU backend
- move TCP headers in TCP backend
- use native serial on Win32 for Cygwin
- avoid too many defines

This change fixes a compilation problem in MinGW. As general rule,
each header must be as independent as possible.