/*
 * mb2hal
 * Userspace HAL component to communicate with one or more Modbus devices.
 *
 * Victor Rocco, adapted from Les Newell's modbuscomms.c which is
 * Copyright (C) 2009-2012 Les Newell <les@sheetcam.com>
 * source code in http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ContributedComponents
 *
 * Copyright (C) 2012 Victor Rocco <victor_rocco AT hotmail DOT com>
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301-1307
 * USA.
 */

2022-10-14:
    - Version 1.1: Added version number for backward compatibility with old pin names
2021-01-17:
    - Added Pins:
      . added bit-inv (invert bit) output for fnct_02_read_discrete_inputs and fnct_01_read_coils
      . added int input for fnct_06_write_single_register and fnct_16_write_multiple_register, 
        renamed float pin to sub-pin '.float'        
    - Added function codes:
      . fnct_01_read_coils
      . fnct_05_write_single_coil
    (Hans Unzner <hansunzner@gmail.com>)

2018-08-19
  # Add fnct_06_write_single_register function as not all devices (e.g.
    Parker AC10 VFD) support fnct_16_write_multiple_registers.
    (Lars Bensmann <lars@almosthappy.de>)

2012-11-12:
  # Arduino example added.
    - Tested with Arduino Mega 2560 R3 using Modbusino over USB at 115200 bps.
  # New parameters in config file.
    - HAL_MODULE_NAME, MB_RESPONSE_TIMEOUT_MS and MB_BYTE_TIMEOUT_MS.
  # New HAL pin "num_errors" for each transaction. num_errors = 0 if last
    transaction OK, else the count of failed transactions.
  # Fix a bug, OPTIONAL's parameters may be 0 instead of default value if
    not specified in 1st transaction.
2012-11-08:
  # Mb2hal now uses libmodbus3 instead of the old libmodbus
    src/hal/user_comps/modbus.c used by gs2_vfd.c
    - Fix some bugs detailed in 2012-10-19.
    - Also fix some things to do detailed in 2012-10-16.
2012-10-19:
  # KNOWN BUGS:
    - Actual modbus.c doesn't handle Modbus errors code correctly, some times
      shows TIME OUT instead of the error code trasmited by the slave.
      Proposal: use the new libmodbus3 instead of modbus.c (Fixed 2012-11-08).
    - Actual modbus.c need a patch "fix tcp protocol error" that is not on master
      (is in 2.5_branch) (Fixed 2012-11-08).
    - Actual modbus.c need the patch 0002-A-number-of-bug-fixes-for-modbus.patch
      by Les Newell, fix compute_response_size and force_multiple_coils
      (fnct_15_write_multiple_coils in mb2hal) (Fixed 2012-11-08).
    - halrun: unloadusr mb2hal or unload mb2hal, mb2hal in defunct state until
      quitting halrun.
    - "Preparing contributions" shows error at creating Debian packages.
      I should ignore them according to emc-devel mailing list responses.
    - Lot of english grammar translations ;=)
  # TESTS:
    - Test 04 OK, all functions.
    - TCP = MoD_RsSim V8.20 (www.plcsimulator.org) on Windows XP SP3.
      . fnct_02_read_discrete_inputs
      . fnct_03_read_holding_registers
      . fnct_04_read_input_registers
      . fnct_15_write_multiple_coils
      . fnct_16_write_multiple_registers
2012-10-16:
  # STATUS:
    - Almost stable, ready to test in depth.
  # TODO list:
    - #include "../modbus.h" must be #include "modbus.h", problem with Submakefile.
      (Fixed 2012-11-08).
    - INI: Optional invert bit, input and output.
    - INI: Optional scaled ints and floats, input and output.
    - INI: hal module name configuration (now is mb2hal).
    - INI: MB_TX_CODE better documentation (Fixed 2012-11-08).
    - HAL example files.
    - INI: better check of parameters not specified and copied from the previous
           link (compare link number instead of type_com).
    - INI: HAL pin names configuration.
    - INI: HAL array of bits from register (integer).
    - Replace actual code based on modbus.c (old libmodbus used by gs2_vfd.c)
      with new code based on libmodbus3 (Fixed 2012-11-08).
    - Incorporate more Modbus functions.
    - Better english translation (I must find someone that want to help).
  # TESTS:
    - Test 01, 02 and 03. All OK.
    - TCP = Remote IO Delta RTU-EN01, 24 inputs, 8 outputs.
      . fnct_02_read_discrete_inputs
      . fnct_15_write_multiple_coils
      . fnct_03_read_holding_registers
    - RS232 = Servo Drive Delta ASDA-B (1021-A 1Kw).
      . fnct_03_read_holding_registers
    - Standalone tests with halrun, not with LinuxCNC.
    - Shutting down both devices and power up again = OK (mb2hal reconnects).
    - 1 Hour continuous functioning shows no errors.
  # CODING STYLE:
    - astyle version 2.02.1
    - astyle -A10s4HUjyk3W3 hal/user_comps/mb2hal/*.c
    - some switches are already in -A10.
    - A10 = 1tbs or otbs, One True Brace Style formatting/indenting.
      Similar to Kernighan & Ritchie style but add brackets to all conditionals.
      Use Linux brackets.
