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

1. Select Modbus/Tcp Client as Channel Type.

2. Click the Configure button.

3. Make sure the root model node is selected to configure the Modbus/TCP Client

4. Enter the IP address and the port

5. (Optional) Change the Connect interval if needed

6. (Optional) Change the Reconnect interval if needed

7. (Optional) Change the Receive interval if needed

8. Select the complex variable node

9. Enable the checkbox TCP Client connection configuration

10. (Optional) Enable Autorefresh to specify the retrieval rate

11. Select the Function Code

12. (Optional) Change the Max update interval if needed

13. Select the complex variable node

14. Enable the checkbox Variables configuration

15. Select the Data type

16. (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