Template:Networking rut manual modbus

Summary

Modbus is a serial communications protocol. Simple and robust, it has since become a de facto standard communication protocol and is now a commonly available means of connecting industrial electronic devices. This chapter is an overview of the Modbus TCP functionality.

Modbus TCP

Modbus TCP provides users with the possibility to set or get system parameters. The Modbus daemon acts as slave device. That means it accepts connections from a master (client) and sends out a response or sets some system related parameter in accordance with the given query.

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:

[[File:{{{modbus_tcp_file}}}]]

Get Parameters

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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:

{{Template: Networking_{{{name}}}_manual_modbus_modbus_tcp_get_parameters_table}}

Set Parameters

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The Modbus daemon can also set some device parameters. These parameters and explanations on how to use them are described in the table below:

{{Template: Networking_{{{name}}}_manual_modbus_modbus_tcp_set_parameters_table}}

* All ON/OFF commands only accept 0 and 1 values, which represent the following:

• 1 - ON
• 0 - OFF

Modbus TCP Master

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, enter a custom name, slave's ID, IP address and port and click the "Add" button:

[[File:{{{file_add_new_slave}}}]]

Slave device configuration

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The figure below is an example of the Slave device configuration and the table below provides information on the fields contained in that section:

[[File:{{{file_slave_configuration}}}]]

Field name	Value	Description
Enabled	yes | no; Default: no	Turns communication with the slave device ON or OFF
Name	string; Default: none	Slave device custom name, used for easier management purposes
Slave ID	integer [1..255]; Default: none	Slave ID. Each slave in a network is assigned a unique identifier randging from 1 to 255. When the master requests data from a slave, the first byte it sends is the Slave ID
IP address	ip; Default: none	Slave device IP address
Port	integer [0..65535]; Default: none	Slave device Modbus TCP port
Period	integer [1..6400]; Default: none	Interval at which requests are sent to the slave device
Timeout	integer [1..30]; Default: none	Maximum response wait time

Requests configuration

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A Modbus request is way of obtaining data from Modbus slaves. The master a sends a request to a slave specifying which Modbus registers should be read. The slave then sends the requested data back to the Modbus master.

The figure below is an example of the Requests configuration section and the table below provides information contained in the fields of that section:

[[File:{{{file_requests}}}]]

Field name	Value	Description
Name	string; Default: Unnamed Parameter	Request name. Used for easier management purposes
Data type	8bit INT | 8bit UINT | 16bit INT, high byte first | 16bit INT, low byte first | 16bit UINT, high byte first | 16bit UINT, low byte first | 32bit float, Byte order 1,2,3,4 | 32bit float, Byte order 4,3,2,1 | 32bit float, Byte order 2,1,4,3 | 32bit float, Byte order 3,4,1,2; Default: 16bit INT, high byte first	Type of data contained in Modbus registers
Function	1 | 2 | 3 | 4 | 5 | 15 | 16; Default: 3
First Register	integer [0..65535]; Default: 1	First Modbus register from which data will be read
Number of Registers	integer [1..2000]; Default: none	Number of Modbus registers that will be read during the request
Enabled	yes | no; Default: no	Turns the request ON or OFF
Test	- (interactive button)	Generates a Modbus request according to given parameters in order to test the request configuration. You must first save the configuration before you can use the Test button
Delete	- (interactive button)	Deletes the request
Add	- (interactive button)	Adds a new request request

Modbus Data to Server

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, enter a custom name, slave's ID, IP address and port and click the "Add" button:

[[File:{{{file_add_new_sender}}}]]

[[File:{{{file_sender_configuration}}}]]

See also

[[Category:{{{name}}} WebUI]]