“Modbus Communication Channels” Tab

Note: For most standard applications, no changes are necessary on this tab.

The “Modbus Communication Channels” tab indicates which Modbus channels/function codes can be used to read and write variables. A distinction is made between generated channels and user-defined channels. These are displayed in the left column of the tab.

Generated Channels are automatically generated from the variables that are created (“Modbus Master Variables” tab) and cannot be changed. You can view the function code used by clicking Generated Channels > WriteSingleRegister. You can also display information on channel variables by clicking Generated Channels > WriteSingleRegister > Output > [Variable Name].

Custom Channels can be created and configured without reference to slave data points.

Modbus Fieldbus Configurator – “Modbus Communication Channels” Tab

For “Custom Channels”, new entries can be created or existing entries deleted via the context menu.

Modbus Communication Channels Context Menu

Modbus Communication Channels Context Menu
Symbol	Button	Description
	[Delete]	Deletes the variable from the master
	[Add]	Creates a new variable on the master
	[Up]	Moves the entry up
	[Down]	Moves the entry down

Other setting options and information are displayed on the right side when an entry is selected on the left side of the tab.

Parameters When “WriteSingleRegister” Selected:

“Communication Channels” Tab (“WriteSingleRegister”)
Parameter	Description
Channel Settings
Function Code	Selection of the function code for read/write operations
Request Cycle Time	Time between two requests
Address/Register (Writing)	Register number that is read/written to
Reading Length	Length of the read request
Writing Length	Length of the write request
Automatic Offset		The memory spacing in the register is calculated automatically.
Automatic Offset		The memory spacing can be set for each variable manually.
Triggering Event – Cyclic		Executes the function code cyclically
Triggering Event – Cyclic		Executes the function code after one or more selected triggering events: Application stop Application start Value change Online change

Parameters When a Variable is Selected:

“Communication Channels” Tab (Variables)
Parameter	Description
Channel Variable
Data Type	Variable data type
Array		Adjust data type to array
Array		Do not change data type
Name	Name of variable Clicking the button to the right of the input field opens the input assistant.
Offset	Memory spacing of the variables in the register (in bits)