zephyr

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Constantin Krischke 8ee675946c modbus: stop bits can now be set individually in client mode Added the stop_bits_client parameter to the modbus_serial_param struct. Being able to configure the number of stop bits for the client independently from the parity setting, allows to support connecting to modbus server that do not follow the MODBUS over Serial Line Specification and Implementation Guide. Signed-off-by: Constantin Krischke <constantin.krischke@lemonbeat.com> Signed-off-by: Jan Geldmacher <jan.geldmacher@lemonbeat.com>		2022-03-24 08:23:17 -04:00
..
src	modbus: stop bits can now be set individually in client mode	2022-03-24 08:23:17 -04:00
app.overlay
CMakeLists.txt
prj.conf
README.rst
sample.yaml

README.rst

.. _modbus-rtu-client-sample:

Modbus RTU Client Sample
########################

Overview
********

This is a simple application demonstrating a Modbus RTU client implementation
in Zephyr RTOS.

Requirements
************

This sample has been tested with the nRF52840-DK and FRDM-K64F boards,
but it should work with any board that has a free UART interface.

RTU client example is running on an evaluation board and communicates
with another board that has been prepared according to the description
`modbus-rtu-server-sample`.

In addition to the evaluation board a RS-485 shield may be used.
The shield converts UART TX, RX signals to RS-485.
An Arduino header compatible shield like `joy-it RS-485 shield for Arduino`_
can be used. This example uses DE signal, which is controlled by pin D9
on the JOY-IT shield. For other shields, ``de-gpios`` property must be adapted
or removed in the application overlay file
:zephyr_file:`samples/subsys/modbus/rtu_client/app.overlay`

The A+, B- lines of the RS-485 shields should be connected together.

Alternatively UART RX,TX signals of two boards can be connected crosswise.

Building and Running
********************

This sample can be found under
:zephyr_file:`samples/subsys/modbus/rtu_client` in the Zephyr tree.

The following commands build and flash RTU client sample.

.. zephyr-app-commands::
   :zephyr-app: samples/subsys/modbus/rtu_client
   :board: frdm_k64f
   :goals: build flash
   :compact:

The example communicates with the RTU server and lets the LEDs light up
one after the other.

.. code-block:: console

   *** Booting Zephyr OS build zephyr-v2.3.0-1993-g07e8d80ae028  ***
   [00:00:00.005,000] <inf> mb_rtu: RTU timeout 2005 us
   [00:00:00.050,000] <inf> mbc_sample: WR|RD holding register:
   48 00 65 00 6c 00 6c 00  6f 00 00 00 00 00 00 00 |H.e.l.l. o.......
   [00:00:00.062,000] <inf> mbc_sample: Coils state 0x00
   [00:00:00.864,000] <inf> mbc_sample: Coils state 0x07


.. _`joy-it RS-485 shield for Arduino`: https://joy-it.net/en/products/ARD-RS485