Lenze E94AxPExxxx - Manual (Page 47)

Lenze · 9400 Servo PLC· Reference manual · DMS 4.0 EN · 11/2013 · TD05/06
47
4 PLC functionality
4.3 Programming notes
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4.3 Programming notes
4.3.1 Update function and scaling function
The update function is used to execute time-consuming calculations - similar to the scaling
functions.
• Scaling functions are always called when the corresponding user code is accessed.
• The update function "listens" to changes that have taken place elsewhere, e.g. changes in the
axis data structure, and executes various calculations again.
Some of the Lenze function blocks have an update function. The update function is not called
automatically by the »9400 ServoPLC«; calling of the function must be programmed.
Lenze function blocks with update function have the following syntax:
• Taskname-FBInstanzname.Update()
• Example: Cam.L_LdVirtualMasterP1.Update();

Tip!
In order to protect the resources, the update function of the function blocks should be
called in an unsolicited task.
Whether a function block has an update function, can be recognised by a corresponding
"Update" entry in the library manager.

Note!
Up to and including version 02.xx.xx , remanent variables support RETAIN and PERSISENT
and RETAIN PERSISTENT are not supported.
From version 03.00.00 , PERSISTENT and PERSISTENT RETAIN are also supported.
• If a persistent variable is linked to a user-defined write/read code, the variable will be
overwritten as follows after the application has been downloaded:
• When the application is downloaded with the »L-force Engineer«, the parameter
set is also loaded into the »9400 ServoPLC«. Thus, the value of this persistent
variable is overwritten by the download depending on the downloaded parameter
value.
• When the application is downloaded with the »PLC Designer«, the user-defined
codes are set to their initial value. Thus, the value of this persistent variable is
overwritten by the download depending on the initial value of the parameter.
• If a persistent variable is linked to a user-defined read code, the value is kept even
after the application has been downloaded.
• The size of the persistent variable memory is limited to 2 kbytes. During the
compilation, an error message is output if this value is exceeded. Please bear in mind
that permanently available contents as e.g. variable names, module names, and data
types reduce the freely available memory space.