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.

The information in this page is updated in accordance with the [[Media:{{{fw_version}}}_WEBUI.bin|{{{fw_version}}}]] firmware version.

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:{{{file_modbus_tcp}}}]]

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}}}]]

Button	Description
Edit	Redirects you to the slave's configuration page (more information in [[{{{name}}} Modbus#Slave_device_configuration|section 3.1]])
Delete	Deletes the slave configuration
Alarms	Redirects you to the slave's alarm configuration page (more information in [[{{{name}}} Modbus#Alarm_configuration|section 3.3]])
Clone	Creates an identical slave configuration

You can create a maximum of 10 slave configurations.

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	Value	Description
Enabled	yes | no; default: no	Turns communication with the slave device on or off.
Name	string; default: none	Slave device's name, used for easier management purposes.
Slave ID	integer [0..255]; default: none	Slave ID. Each slave in a network is assigned a unique identifier ranging from 1 to 255. When the master requests data from a slave, the first byte it sends is the Slave ID. When set to 0, the slave will respond to requests addressed to any ID.
IP address	ip; default: none	Slave device's IP address.
Port	integer [0..65535]; default: none	Slave device's 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 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. 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:

[[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	How read data will be stored
Function	1 | 2 | 3 | 4 | 5 | 6 | 15 | 16; Default: 3	A function code specifies the type of register being addressed by a Modbus request. The codes represent these functions: 1 - read Coil Status 2 - read Input Status 3 - read Holding Registers 4 - read Input Registers 5 - force Single Coil 6 - preset Single Register 15 - force Multiple Coils 16 - force Multiple Registers
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 configuration

Alarm configuration

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Alarms are way of setting up automated actions when some Modbus values meet user specified conditions. The figure below is an example of the Alarm configuration page and the table below provides information on fields that it contains:

[[File:{{{file_alarms}}}]]

Field	Value	Description
Enabled	yes | no; default: no	Turns the alarm on or off
Function code	Read Coil Status (1) | Read Input Status (2) | Read Holding Registers (3) | Read Input Registers (4); default: Read Coil Status (1)	Modbus function used in Modbus request.
Register	integer [0..65535]; default: none	Number of the Modbus coil/input/holding register/input register that will be read.
Condition	More than | Less than | Equal to | Not Equal to; default: Equal to	When a value is obtained it will be compared against the value specified in the following field. The comparison will be made in accordance with the condition specified in this field.
Value	various; default: none	The value against which the read data will be compared.
Action	SMS | Trigger output | Modbus Request; default: SMS	Action that will be taken if the condition is met. Possible actions: SMS - sends and SMS message to a specified recipient(s). Trigger output - changes the state of a specified output(s). Modbus Request - sends a Modbus request to a specified slave.
SMS: Message	string; default: none	SMS message text.
SMS: Phone number	phone number; default: none	Recipient's phone number.
Trigger output: Output	Open collector output | Relay output | Both; default: Open collector output	Which output(s) will be triggered.
Trigger output: I/O Action	Turn On | Turn Off | Invert; default: Turn On	Action that will taken on the specified output.
Modbus Request: IP address	ip | host; default: none	Modbus slave's IP address.
Modbus Request: Port	integer [0..65535]; default: none	Modbus slave's port.
Modbus Request: Timeout	integer [1..30]; default: 5	Maximum time to wait for a response.
Modbus Request: ID	integer [1..255]; default: none	Modbus slave ID.
Modbus Request: Modbus function	Read Coil Status (1) | Read Input Status (2) | Read Holding Registers (3) | Read Input Registers (4) | Force Single Coil (5) | Preset Single Register (6) | Force Multiple Coils (15) | Force Multiple Registers (16); default: Force Single Coil (5)	A function code specifies the type of register being addressed by a Modbus request.
Modbus Request: First register	integer [0..65535]; default: none	Begins reading from the register specified in this field.
Modbus Request: Number of registers	integer [0..65535]; default: none	The number of registers that will be read from the first register.

Modbus Serial Master

RS232

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[[File:{{{file_rs232}}}]]

Field	Value	Description
Enabled	yes | no; default: no	Turns the Modbus RTU via RS232 on or off.
Baud rate	300 | 1200 | 2400 | 4800 | 9600 | 19200 | 38400 | 57600 | 115200; default: 19200	Serial data transmission rate (in bits per second).
Data bits	5 | 6 | 7 | 8; default: 8	Number of data bits of each character.
Parity	None | Even | Odd; default: Even	In serial transmission, parity is a method of detecting errors. An extra data bit is sent with each data character, arranged so that the number of 1 bits in each character, including the parity bit, is always odd or always even. If a byte is received with the wrong number of 1s, then it must have been corrupted. However, an even number of errors can pass the parity check. None (N) - no parity method is used. Odd (O) - the parity bit is set so that the number of "logical ones (1s)" has to be odd. Even (E) - the parity bit is set so that the number of "logical ones (1s)" has to be even.
Stop bits	1 | 2; default: 1	Stop bits sent at the end of every character allow the receiving signal hardware to detect the end of a character and to resynchronise with the character stream. Electronic devices usually use one stop bit. Two stop bits are required if slow electromechanical devices are used.
Flow control	None | RTS/CTS | Xon/Xoff; default: None	In many circumstances a transmitter might be able to send data faster than the receiver is able to process it. To cope with this, serial lines often incorporate a "handshaking" method, usually distinguished between hardware and software handshaking. RTS/CTS - hardware handshaking. RTS and CTS are turned OFF and ON from alternate ends to control data flow, for instance when a buffer is almost full. Xon/Xoff - software handshaking. The Xon and Xoff characters are sent by the receiver to the sender to control when the sender will send data, i.e., these characters go in the opposite direction to the data being sent. The circuit starts in the "sending allowed" state. When the receiver's buffers approach capacity, the receiver sends the Xoff character to tell the sender to stop sending data. Later, after the receiver has emptied its buffers, it sends an Xon character to tell the sender to resume transmission.

RS485

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[[File:{{{file_rs485}}}]]

Field	Value	Description
Enabled	yes | no; default: no	Turns the Modbus RTU via RS485 on or off.
Baud rate	300 | 1200 | 2400 | 4800 | 9600 | 19200 | 38400 | 57600 | 115200; default: 19200	Serial data transmission rate (in bits per second).
Data bits	5 | 6 | 7 | 8; default: 8	Number of data bits of each character.
Parity	None | Even | Odd; default: Even	In serial transmission, parity is a method of detecting errors. An extra data bit is sent with each data character, arranged so that the number of 1 bits in each character, including the parity bit, is always odd or always even. If a byte is received with the wrong number of 1s, then it must have been corrupted. However, an even number of errors can pass the parity check. None (N) - no parity method is used. Odd (O) - the parity bit is set so that the number of "logical ones (1s)" has to be odd. Even (E) - the parity bit is set so that the number of "logical ones (1s)" has to be even.
Stop bits	1 | 2; default: 1	Stop bits sent at the end of every character allow the receiving signal hardware to detect the end of a character and to resynchronise with the character stream. Electronic devices usually use one stop bit. Two stop bits are required if slow electromechanical devices are used.
Flow control	None | RTS/CTS | Xon/Xoff; default: None	In many circumstances a transmitter might be able to send data faster than the receiver is able to process it. To cope with this, serial lines often incorporate a "handshaking" method, usually distinguished between hardware and software handshaking. RTS/CTS - hardware handshaking. RTS and CTS are turned OFF and ON from alternate ends to control data flow, for instance when a buffer is almost full. Xon/Xoff - software handshaking. The Xon and Xoff characters are sent by the receiver to the sender to control when the sender will send data, i.e., these characters go in the opposite direction to the data being sent. The circuit starts in the "sending allowed" state. When the receiver's buffers approach capacity, the receiver sends the Xoff character to tell the sender to stop sending data. Later, after the receiver has emptied its buffers, it sends an Xon character to tell the sender to resume transmission.

Slaves

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[[File:{{{file_slave_settings}}}]]

Field	Value	Description
Enabled	yes | no; default: no	Turns the slave on or off.
Slave ID	integer [1..255]; default: 1	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.
Period	integer [1..9999]; default: 10	Interval (in minutes) at which requests are sent to the slave device.

Slave requests

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[[File:{{{file_slave_request}}}]]

Field	Value	Description
Enabled	yes | no; default: no	Turns the request on or off.
Function	Read Coil | Read Discrete Input | Read Holding Registers | Read Input Registers; default: Read Holding Registers	Modbus function used in Modbus request.
First Register	integer [1..65536]; 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/

Slave alarms

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[[File:{{{file_slave_alarm}}}]]

Field	Value	Description
Enabled	yes | no; default: no	Turns the alarm on or off.
Function	Read Coil | Read Discrete Input | Read Holding Registers | Read Input Registers; default: Read Holding Registers	Modbus function used in Modbus request.
Register	integer [1..65536]; default: 1	Number of the Modbus coil/input/holding register/input register that will be read.
Condition	More than | Less than | Equal to | Not equal to; default: More than	When a value is obtained it will be compared against the value specified in the following field. The comparison will be made in accordance with the condition specified in this field.
Value	integer [0..65535]; default: 0	The value against which the read data will be compared.
Action	SMS | Trigger output | Modbus request; default: SMS	Action that will be taken if the condition is met. Possible actions: SMS - sends and SMS message to a specified recipient(s). Trigger output - changes the state of a specified output(s). Modbus Request - sends a Modbus request to a specified slave.

Modbus Data to Server

The Modbus Data to Server function provides you with the possibility to set up senders that transfer data collected from Modbus slaves to remote servers. To add a new data sender, enter the server's address, specify the data sending period and click the "Add" button:

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

Data sender configuration

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When you add a new data sender, you will be redirected to its configuration window. The figure below is an example of that window and the table below provides information on the fields that it contains:

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

Enabled	yes | no; Default: no	Turns the data sender ON or OFF
Name	string; Default: none	Data sender's name. used for easier management purposes
Protocol	HTTP(S); Default: HTTP(S)	Data sending protocol
JSON format	json string; Default: {"ID":"%i", "TS":"%t","ST":"%s","VR":"%a"}	Provides the possibility to fully customize the JSON segment
Segment count	1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10; Default: 1	Max segment count in one JSON string sent to server
URL	host | ip; Default: none	Address of the server to which the data will be sent. . Important note: when using HTTPS, remember to add the https:// prefix before the URL
Period	integer [1..6400]; Default: none	Data sending frequency (in seconds)
Data filtering	All data | By slave ID | By slave IP; Default: All data	Which data this sender will transfer to the server
Retry on fail	yes | no; Default: no	Specifies whether the data sender should retry failed attempts
Custom header	string; Default: no	Adds a custom header(s) to HTTP requests

See also

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