Modbus is a serial communications protocol. Simple and robust, it has become a de facto standard communication protocol and is now a commonly available means of connecting industrial electronic devices.
This manual page provides an overview of the Modbus functionality in RUTX11 devices.
If you’re having trouble finding this page or some of the parameters described here on your device’s WebUI, you should turn on “Advanced WebUI” mode. You can do that by clicking the “Basic” button under “Mode”, which is located at the top-right corner of the WebUI.
A Modbus TCP slave listens for connections from a master (client) and sends out a response or sets some system related parameter in accordance with the given query. This provides the user with the possibility to set or get system parameters.
The figure below is an example of the Modbus TCP window section and the table below provides information on the fields contained in that window:
Modbus parameters are held within registers. Each register contains 2 bytes of information. For simplification, the number of registers for storing numbers is 2 (4 bytes), while the number of registers for storing text information is 16 (32 bytes). The register numbers and corresponding system values are described in the table below:
The Modbus daemon can also set some device parameters. These parameters and explanations on how to use them are described in the table below:
A Modbus master device can request data from Modbus slaves. The Modbus TCP Master section is used to configure Modbus TCP slaves.
To add a new slave, simply click the ‘Add’ button.
You can create a maximum of 10 slave configurations.
The figure below is an example of the Slave device configuration and the table below provides information on the fields contained in that section:
A Modbus request is a way of obtaining data from Modbus slaves. The master sends a request to a slave specifying the function code to be performed. The slave then sends the requested data back to the Modbus master. You can create a maximum of 64 request configurations for each slave device.
The figure below is an example of the Requests configuration section and the table below provides information contained in the fields of that section:
After having configured a request, you should see a new ‘Testing’ section appear. It is used to check whether the configuration works correctly. Simply press the ‘Test’ button and a response should appear in the box below.
Alarms are a way of setting up automated actions when some Modbus values meet user specified conditions. The figure below is an example of the Alarms Configuration list.
It is empty by default. So, to begin editing click the ‘Add’ button and you should be redirected to a page such as this:
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