61
Creating a variable
This section introduces how to create and declare variables to
diagnose and monitor the system.
To create a variable
1. Click IEC Programming Workspace from the toolbar, or from Home
Page, click Program with IEC61131-3.
2. You can create local variables or global variables from the
corresponding grid worksheet. is the grid worksheet for local
variables, and is the grid worksheet for global variables.
For the following steps, let us take the global variable as an
example.
3. Double-click Global_Variables under Physical Hardware, the global
variable sheet appears.
4. Right-click under the corresponding group, and select Insert
variable to add a new I/O variable.
For output channel variables, you must add corresponding read
back variables with suffix “_READBACK” in the Input I/O Variables
group.
5. Double-click the Name and Description fields to modify, and select
Type and Usage from the drop-down lists.
The maximum quantity of characters for a variable name is 30.
IEC address of the I/O variable is generated automatically after
you bind it with an I/O channel and click Make. If you add a new
I/O variable by copying an existing bound one in a compiled
project, you should delete the IEC address of the new variable
manually and click Make to generate it automatically.
6. If a variable will be used for Modbus, EFM or PID, you should
select Retain for it. Perform either of the following methods:
l From the variable sheets, select Retain.
Chapter 4 - Software
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