Modbus¶

Characteristics - Modbus¶

MODBUS is an application-layer messaging protocol, positioned at level 7 of the OSI model. It provides client/server communication between devices connected on different types of buses or networks. To learn more about the standard visit the MODBUS website.

Information Model Requirements

The following Node Types can be used to model a register:
- Variables with a Simple Data Type.
- Variables with a Custom Data Type.

Configuration - Modbus¶

Select Modbus/Tcp Client as Channel Type.
Click the Configure button.

Make sure the root model node is selected to configure the Modbus/TCP Client
Enter the IP address and the port
(Optional) Change the Connect interval if needed
(Optional) Change the Reconnect interval if needed
(Optional) Change the Receive interval if needed

Select the complex variable node
Enable the checkbox TCP Client connection configuration
(Optional) Enable Autorefresh to specify the retrieval rate
Select the Function Code
(Optional) Change the Max update interval if needed

Select the complex variable node
Enable the checkbox Variables configuration
Select the Data type
(Optional) Enter the register address

Note

If address is left empty, SMARTUNIFIER assumes that the Information Model structure is in line with the register addresses.

Description of data type format:

Data Type	Size	Range
BYTE, USINT, UInt8	8 Bit	`0 - 255`
WORD, UINT, UInt16	16 Bit	`0 - 65.535`
DWORD,UDINT, UInt32	32 Bit	`0 - 4.294.967.295`
LWORD,ULINT, UInt64	64 Bit	`0 - 2^64-1`
SINT, Int8	8 Bit	`–128 - 127`
INT, Int16	16 Bit	`–32.768 - 32.767`
DINT, Int32	32 Bit	`–2.147.483.648 - 2.147.483.647`
LINT, Int64	64 Bit	`–2^63 - 2^63-1`
REAL, Float32	32 Bit	`-3,402823e+38 - 3,402823e+38`
LREAL, Float64	64 Bit	`-1,7976931348623158e+308 - 1,7976931348623158e+308`

Description of configuration properties:

Property	Description	Example
IP	Client IP	`localhost`
Port	Client port	`502`
Connection timeout	Time interval the connection times out	`60`
Reconnect interval	Time interval to reconnect to the client after loss of connection	`5`
Receive interval	TCP/IP receive timeout	`50`
Autorefresh	Automatic polling of Modbus server	`2`
Read function code	Function code used for reading variables from a modbus server	`FC04`
Max update interval	Minimum time between requests to the Modbus server (if autorefresh is not used)	`60`
Variable configuration Type	Format of variable	`DWORD`
Variable configuration Address	Address of the variable on the modbus server	`0`