122 lines
6.1 KiB
Markdown
122 lines
6.1 KiB
Markdown
# Modbus
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This directory contains a port of last open source version of FreeModBus (BSD
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license). The code in this directory is a subset of FreeModBus version 1.5.0
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(June 6, 2010) that can be downloaded in its entirety from
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http://developer.berlios.de/project/showfiles.php?group_id=6120.
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Includes extensions to support RTU master mode by Armink(383016632@qq.com):
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https://github.com/armink/FreeModbus_Slave-Master-RTT-STM32. Ported to NuttX by
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Darcy Gong.
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## Directory Structure / Relation to freemodbus-v1.5.0
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The original FreeModBus download consists of several directories. This subset
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takes only the contents of one directory, `modbus/`, that implements the core
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modbus logic and integrates that directory into the NuttX build system. The
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mapping between `freemodbus-v1.5.0` and the nuttx directories is shown below:
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```
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--------------------------- ----------------------------------------------
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freemodbus-v1.5.0 NuttX
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--------------------------- ----------------------------------------------
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All top level .txt files Not included
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demo/ Not included. This directory contains demo
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and porting code for a variety of platforms.
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The NuttX demo was ported from the LINUX
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demo in this directory and can be found at
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apps/examples/modbus.
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doc/ Not included. This directory contains Doxygen
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support files.
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modbus/ Included in its entirety in various locations:
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ascii apps/modbus/ascii
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functions apps/modbus/functions
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include apps/include/modbus
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mb.c apps/modbus/mb.c
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rtu apps/modbus/rtu
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tcp apps/modbus/tcp
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tools/ Not included. This directory contains Doxygen
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tools.
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--------------------------- ----------------------------------------------
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```
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So this directory is equivalent to the `freemodbus-v1.5.0/modbus` directory
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except that (1) it may include modifications for the integration with NuttX and
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(2) the modbus/include directory was moved to `apps/modbus`.
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The original, unmodified `freemodbus-v1.5.0` was checked in as SVN revision
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`4960`.
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The other directory here, `nuttx/`, implements the NuttX modbus interface. It
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derives from the `freemodbus-v1.5.0/demo/LINUX/port` directory.
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## Configuration Options
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In the original `freemodbus-v1.5.0` release, the FreeModBus configuration was
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controlled by the header file `mbconfig.h`. This header file was eliminated
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(post revision `4960`) and the FreeModBus configuration was integrated into the
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NuttX configuration system.
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The NuttX-named configuration options that are available include:
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- `CONFIG_MODBUS` – General ModBus support.
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- `CONFIG_MB_ASCII_ENABLED` – Modbus ASCII support.
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- `CONFIG_MB_ASCII_MASTER` – Modbus ASCII master support.
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- `CONFIG_MB_RTU_ENABLED` – Modbus RTU support.
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- `CONFIG_MB_RTU_MASTER` – Modbus RTU master support.
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- `CONFIG_MB_TCP_ENABLED` – Modbus TCP support.
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- `CONFIG_MB_ASCII_TIMEOUT_SEC` – Character timeout value for Modbus ASCII. The
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character timeout value is not fixed for Modbus ASCII and is therefore a
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configuration option. It should be set to the maximum expected delay time of
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the network. Default: `1`.
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- `CONFIG_MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS` – Timeout to wait in ASCII prior
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to enabling transmitter. If defined the function calls `vMBPortSerialDelay`
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with the argument `CONFIG_MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS` to allow for a
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delay before the serial transmitter is enabled. This is required because some
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targets are so fast that there is no time between receiving and transmitting
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the frame. If the master is too slow with enabling its receiver then it will
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not receive the response correctly.
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- `CONFIG_MB_FUNC_HANDLERS_MAX` – Maximum number of Modbus functions codes the
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protocol stack should support. The maximum number of supported Modbus
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functions must be greater than the sum of all enabled functions in this file
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and custom function handlers. If set too small, adding more functions will
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fail.
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- `CONFIG_MB_FUNC_OTHER_REP_SLAVEID_BUF` – Number of bytes which should be
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allocated for the Report Slave ID command. This number limits the maximum size
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of the additional segment in the report slave id function. See
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`eMBSetSlaveID()` for more information on how to set this value. It is only
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used if `CONFIG_MB_FUNC_OTHER_REP_SLAVEID_ENABLED` is set to `1`.
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- `CONFIG_MB_FUNC_OTHER_REP_SLAVEID_ENABLED` – If the Report Slave ID function
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should be enabled.
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- `CONFIG_MB_FUNC_READ_INPUT_ENABLED` – If the Read Input Registers function
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should be enabled.
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- `CONFIG_MB_FUNC_READ_HOLDING_ENABLED` – If the Read Holding Registers function
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should be enabled.
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- `CONFIG_MB_FUNC_WRITE_HOLDING_ENABLED` – If the Write Single Register function
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should be enabled.
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- `CONFIG_MB_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED` – If the Write Multiple
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registers function should be enabled.
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- `CONFIG_MB_FUNC_READ_COILS_ENABLED` – If the Read Coils function should be
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enabled.
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- `CONFIG_MB_FUNC_WRITE_COIL_ENABLED` – If the Write Coils function should be
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enabled.
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- `CONFIG_MB_FUNC_WRITE_MULTIPLE_COILS_ENABLED` – If the Write Multiple Coils
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function should be enabled.
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- `CONFIG_MB_FUNC_READ_DISCRETE_INPUTS_ENABLED` – If the Read Discrete Inputs
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function should be enabled.
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- `CONFIG_MB_FUNC_READWRITE_HOLDING_ENABLED` – If the Read/Write Multiple
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Registers function should be enabled.
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See also other serial settings, in particular:
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- `CONFIG_SERIAL_TERMIOS` – Serial driver supports `termios.h` interfaces
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(`tcsetattr`, `tcflush`, etc.). If this is not defined, then the terminal
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settings (baud, parity, etc.) are not configurable at runtime; serial streams
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will not be flushed when closed.
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## Note
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The developer of FreeModBus, Christian Walter, is still developing Modbus
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libraries, although they are now commercial. See
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http://www.embedded-solutions.at/ for further information.
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