letscontrolit · flashmark · Aug 24, 2025 · Aug 24, 2025 · Aug 27, 2025 · Aug 28, 2025
diff --git a/docs/source/Interfaces/Interfaces.rst b/docs/source/Interfaces/Interfaces.rst
@@ -205,5 +205,16 @@ NB: When selecting the *User-defined* option, **all 3 GPIO pins should be set**,
 Modbus
 ------
 
-TODO Modbus configuration and documentation to be added.
+When using devices that use the Modbus RTU protocol the Modbus interface can be configured here. The Modbus RTU devices are connected via a RS485 serial interface. Multiple devices can be connected to the same serial interface, and are distinguished by their Modbus address. Note that a serial to RS485 converter is required to connect Modbus RTU devices to the ESP board. 
 
+.. image:: Modbus_Interface.png
+
+Main configuration item is the selection of the serial interface to use for Modbus. The available options depend on the ESP board used. For details about the available serial interfaces, see  serial helper page. The option "Not set" means that Modbus link is not used. When a serial interface is selected, it will be initialized and the Modbus RTU devices can be connected to it.
+
+Selection of the RX and TX  pins is required.
+
+The Modbus RTU devices are connected to the selected serial interface via a RS485 converter. The converter has a DE (Driver Enable) pin that can be controlled by the ESP board to switch between sending and receiving data. The DE pin can be configured here. If the converter has an automatic DE function, this can be set to "-None-".  
+
+The Baud rate for the Modbus RTU communication shall be set. The default value is 9600 baud, but it can be set to other values as required by the connected devices.
+
+Collision Detection is a feature that can be used when the serial port hardware supports it, otherwise it is ignored.
diff --git a/docs/source/Interfaces/Modbus_Interface.png b/docs/source/Interfaces/Modbus_Interface.png
diff --git a/docs/source/Plugin/P183.rst b/docs/source/Plugin/P183.rst
@@ -0,0 +1,123 @@
+.. include:: ../Plugin/_plugin_substitutions_p18x.repl
+.. _P183_page:
+
+|P183_typename|
+==================================================
+
+|P183_shortinfo|
+
+Plugin details
+--------------
+
+Type: |P183_type|
+
+Port Type: |P183_porttype|
+
+Name: |P183_name|
+
+Status: |P183_status|
+
+GitHub: |P183_github|_
+
+Maintainer: |P183_maintainer|
+
+Used libraries: |P183_usedlibraries|
+
+Introduction
+------------
+
+Modbus is a serial communication protocol commonly used for connecting industrial electronic devices. 
+It is a master/slave (or client/server) protocol, which means that one device (the master) initiates communication and the other devices (the slaves) respond. 
+Modbus RTU (Remote Terminal Unit) is a variant of the Modbus protocol that uses binary representation of data and is typically used over serial communication lines such as RS-485 or RS-232.
+This plugin supports Modbus RTU communication over a serial interface. To support RS-485 communication, an external RS-485 to TTL converter is required.
+
+Modbus RTU uses a register-based addressing scheme, where each device has a unique address and data is stored in registers.
+Registers can be of different types, such as holding registers, input registers, coils, and discrete inputs.
+This plugin supports reading holding registers (function code 03) and writing to holding registers (function code 06).
+
+The plugin can be configured to read up to 4 holding registers from a Modbus slave device and store the values in user variables.
+It can also write values to a specified holding register on the Modbus slave device. 
+
+The plugin does not support any hardware specific features. Instead it is a generic plugin that can be used with any Modbus RTU compatible device. You have to lookup the correct register addresses and data formats in the documentation of the Modbus device you want to communicate with.
+
+Supported hardware
+------------------
+
+|P183_usedby|
+
+Configuration
+-------------
+
+* **Name**: Required by ESPEasy, must be unique among the list of available devices/tasks.
+
+* **Enabled**: The device can be disabled or enabled. When not enabled the device should not use any resources.
+
+Sensor
+^^^^^^
+
+.. image:: P183_device_settings.png
+
+The available Modbus protocol settings here depend on the build used.
+
+* **Modbus Link**: The Modbs link teh device is connected to. The link must be configured in the Interafces page.
+
+* **Modbus Device Address**: The Modbus slave device ID to communicate with (1..247).
+
+Output Configuration
+^^^^^^^^^^^^^^^^^^^^
+
+.. image:: P183_output_config.png
+
+* **Number of registers to read**: The number of holding registers the plugin will read (1..4).
+
+* **Holding register for valueX**: The Modbus holding register address to read for valueX (X=1..4).
+
+The holding register address is a 16-bit value (0..65535). This is the register address as specified with the Modbus device and is used directly in the Modbus read holding registers (function code 03). The plugin will read the number of values specified, starting with value1
+
+Commands available
+^^^^^^^^^^^^^^^^^^
+
+.. include:: P183_commands.repl
+
+.. Events
+.. ~~~~~~
+
+.. .. include:: P183_events.repl
+
+Get Config Values
+^^^^^^^^^^^^^^^^^
+
+Get Config Values retrieves values or settings from the sensor or plugin, and can be used in Rules, Display plugins, Formula's etc. The square brackets **are** part of the variable. Replace ``<taskname>`` by the **Name** of the task.
+
+.. include:: P183_config_values.repl
+
+Plugin state
+------------
+
+This plugin uses a new Modbus facility that allows multiple Modbus devices to share the same Modbus link.
+The current implementataion of the Modbus facility requires that the plugin specifies the serial link parameters.
+When a Modbus link is shared between multiple plugins, the last plugin that connects to the Modbus link will determine the serial link parameters.
+This may lead to unexpected behavior if multiple plugins are using different serial link parameters on the same serial port. For a deterministic behavior, make sure that all plugins using the same serial port use the same serial link parameters.
+
+In the future the Modbus facility may be extended to configure the Modbus links as separate entities. As a result the plugins would only need to specify which Modbus link to use, instead of the serial link parameters. 
+This change will be backward incompatible with the current implementation. Therefore the plugin status is set to 'Experimental'.
+
+Change log
+----------
+
+.. versionchanged:: 2.0
+  ...
+
+  |added|
+  Major overhaul for 2.0 release.
+
+.. versionadded:: 1.0
+  ...
+
+  |added|
+  Initial release version.
+
+
+
+
+
diff --git a/docs/source/Plugin/P183_commands.repl b/docs/source/Plugin/P183_commands.repl
@@ -0,0 +1,28 @@
+.. csv-table::
+        :header: "Command", "Extra information"
+        :widths: 20, 30
+
+        "
+        ``modbus,write,<address>,<value>``
+
+        ","
+        Write value ``<value>`` into the holding register ``<address>``.
+        "
+        "
+        ``modbus,read,<address>``
+
+        ","
+        Read the value from the holding register ``<address>``. Note that the value is read from the Modbus device but it will not be returned as part of the command. The value is printed in the logging.
+        "
+        "
+        ``modbus,scan``
+
+        ","
+        Scans the modbus address range for responding units. It will do a read function for holding register 1. Note this will take some time. Ouput is in the logging.
+        "
+              "
+        ``modbus,dump,<start>,<end>``
+
+        ","
+        Dumps the holding registers in the  address range ``<start>`` until ``<end>``.
+        "
diff --git a/docs/source/Plugin/P183_config_values.repl b/docs/source/Plugin/P183_config_values.repl
@@ -0,0 +1,10 @@
+.. csv-table::
+    :header: "Config value", "Information"
+    :widths: 20, 30
+
+    "
+    | ``[<taskname>#register,<reg>]``
+    ","
+    | Returns the value of holding register ``<reg>`` of the device. The value is directly read from the Modbus device. The holding register number ``<reg>`` can be any valid register in the device.
+    "
+
diff --git a/docs/source/Plugin/P183_device_settings.png b/docs/source/Plugin/P183_device_settings.png
diff --git a/docs/source/Plugin/P183_output_config.png b/docs/source/Plugin/P183_output_config.png
diff --git a/docs/source/Plugin/_Plugin.rst b/docs/source/Plugin/_Plugin.rst
@@ -509,7 +509,7 @@ There are different released versions of ESP Easy:
    ":ref:`P177_page`","|P177_status|","|P177_status_lb|","P177"
    ":ref:`P178_page`","|P178_status|","|P178_status_lb|","P178"
    ":ref:`P180_page`","|P180_status|","|P180_status_lb|","P180"
-
+   ":ref:`P183_page`","[P183_status]","[P183_status_lb]","P183"
 
 .. include:: <isonum.txt>
 .. include:: _plugin_sets_overview.repl

diff --git a/docs/source/Plugin/_plugin_categories.repl b/docs/source/Plugin/_plugin_categories.repl
@@ -1,7 +1,7 @@
 .. |Plugin_Analog_input| replace:: :ref:`P002_page`, :ref:`P007_page`, :ref:`P025_page`, :ref:`P060_page`, :ref:`P097_page`
 .. |Plugin_Acceleration| replace:: :ref:`P120_page`, :ref:`P125_page`
 .. |Plugin_Color| replace:: :ref:`P112_page`
-.. |Plugin_Communication| replace:: :ref:`P016_page`, :ref:`P020_page`, :ref:`P035_page`, :ref:`P044_page`, :ref:`P054_page`, :ref:`P071_page`, :ref:`P087_page`, :ref:`P089_page`, :ref:`P094_page`, :ref:`P101_page`, :ref:`P118_page`, :ref:`P176_page`
+.. |Plugin_Communication| replace:: :ref:`P016_page`, :ref:`P020_page`, :ref:`P035_page`, :ref:`P044_page`, :ref:`P054_page`, :ref:`P071_page`, :ref:`P087_page`, :ref:`P089_page`, :ref:`P094_page`, :ref:`P101_page`, :ref:`P118_page`, :ref:`P176_page`, :ref:`P183_page`
 .. |Plugin_Display| replace:: :ref:`P012_page`, :ref:`P023_page`, :ref:`P036_page`, :ref:`P057_page`, :ref:`P073_page`, :ref:`P075_page`, :ref:`P095_page`, :ref:`P104_page`, :ref:`P116_page`, :ref:`P131_page`, :ref:`P148_page`
 .. |Plugin_Distance| replace:: :ref:`P013_page`, :ref:`P110_page`, :ref:`P113_page`, :ref:`P134_page`
 .. |Plugin_Dust| replace:: :ref:`P018_page`, :ref:`P053_page`, :ref:`P056_page`, :ref:`P144_page`, :ref:`P175_page`