62 lines
2.0 KiB
ReStructuredText
62 lines
2.0 KiB
ReStructuredText
.. _modbus-rtu-client-sample:
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Modbus RTU Client Sample
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########################
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Overview
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********
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This is a simple application demonstrating a Modbus RTU client implementation
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in Zephyr RTOS.
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Requirements
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************
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This sample has been tested with the nRF52840-DK and FRDM-K64F boards,
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but it should work with any board that has a free UART interface.
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RTU client example is running on an evaluation board and communicates
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with another board that has been prepared according to the description
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`modbus-rtu-server-sample`.
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In addition to the evaluation board a RS-485 shield may be used.
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The shield converts UART TX, RX signals to RS-485.
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An Arduino header compatible shield like `joy-it RS-485 shield for Arduino`_
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can be used. This example uses DE signal, which is controlled by pin D9
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on the JOY-IT shield. For other shields, ``de-gpios`` property must be adapted
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or removed in the application overlay file
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:zephyr_file:`samples/subsys/modbus/rtu_client/app.overlay`
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The A+, B- lines of the RS-485 shields should be connected together.
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Alternatively UART RX,TX signals of two boards can be connected crosswise.
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Building and Running
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********************
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This sample can be found under
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:zephyr_file:`samples/subsys/modbus/rtu_client` in the Zephyr tree.
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The following commands build and flash RTU client sample.
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.. zephyr-app-commands::
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:zephyr-app: samples/subsys/modbus/rtu_client
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:board: frdm_k64f
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:goals: build flash
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:compact:
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The example communicates with the RTU server and lets the LEDs light up
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one after the other.
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.. code-block:: console
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*** Booting Zephyr OS build zephyr-v2.3.0-1993-g07e8d80ae028 ***
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[00:00:00.005,000] <inf> mb_rtu: RTU timeout 2005 us
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[00:00:00.050,000] <inf> mbc_sample: WR|RD holding register:
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48 00 65 00 6c 00 6c 00 6f 00 00 00 00 00 00 00 |H.e.l.l. o.......
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[00:00:00.062,000] <inf> mbc_sample: Coils state 0x00
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[00:00:00.864,000] <inf> mbc_sample: Coils state 0x07
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.. _`joy-it RS-485 shield for Arduino`: https://joy-it.net/en/products/ARD-RS485
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