Master Variables (Slave Data Points on the Master)

Clicking [Map] carries the slave data points over to the master and displays them as master variables on the left side in tabular form as follows:

“Modbus Master Variables” – Slave Data Points on the Master (Left Side)
Parameter	Description
Data Point (Slave)	Name and path of the slave data point on the master
Variable	Variable name and path on the master A general distinction is made between manual and automatic variants:
	Automatic	A variable is created according to the variable path on the master.
	Manual	The variable is entered by the user. It can be an existing variable or one created by CODESYS.
Mapping	Indicates which variable is new and which variable already exists:
		The variable is not yet available, will be newly created and can then be used in the entire project.
		An existing variable is used for mapping.
Data Type	Drop-down list for carrying over the (slave) data type
T [ms]	Cycle time for access to the data point
Access	Access to the variable of the Modbus slave is specified:
	ReadOnly	The master reads the slave output.
	WriteOnly	The master writes the slave input.
	ReadWrite	The master can write/read the slave input/output.
Trigger	Defines the time access The selection operation depends on the access setting.
	Cyclic	Variable is processed cyclically
	OnValue Change	Variable is written on change of value (with “WriteOnly” and “ReadWrite” only)

Note

Simultaneous access from several tasks to one variable leads to inconsistencies!

Do not access the same Modbus variable from several tasks. This may lead to inconsistencies. It is not guaranteed that the Modbus variable provides the expected value. You will not receive an error message for this.

Right-clicking on the master variable or the slave data point that has been provided opens a context menu:

Slave Variables Context Menu
Symbol	Parameter	Description
	Delete	Deletes the slave data point on the master The master variable is also deleted unless it is a global variable.
	Reset	Resets the master variable to “automatic value”
	Transfer	Carries the value of the cell over to all selected rows (T [ms], Trigger, Access)