Siemens SINUMERIK 828D Function Manual page 921

• Select variable
A variable is selected by means of a simple mouse click and transferred to the window of selected variables
by double-clicking. This action can also be undone under the "Edit" menu item.
Alias name
The variable names provided can be up to 32 characters in length. To make variables clearly identifiable in the
data block to be generated, several ASCII characters are added to the selected name. However, the STEP 7
compiler recognizes only 24 ASCII characters as an unambiguous STEP 7 variable. Since it cannot be precluded
that variable names can only be differentiated by the last 8 character positions, ALIAS names are used for
names, which are too long. When a variable is selected, the length of the STEP7 name to be used is, therefore,
checked. If the name is longer than 24 characters, the user must enter an additional name, which is then used as
the alias.
In this case, the user must ensure that the alias name is unambiguous.
Alias input can always be activated by the user in the "Options" menu.
An alias name can then be entered every time a variable is transferred.
It is also possible to edit alias names at a later point in time by double­clicking on the S7 variable name field. This
action can also be undone under the "Edit" menu item.
Figure 13-27 Screen with complete list and selected variables
Scrolling
A scroll bar is displayed if it is not possible to display all variables in the window. The remaining variables can be
reached by scrolling (page up/down).
Variables in multi-dimensional structures
If variables are selected from multi­dimensional structures, then the column and/or line number as well as the
area number must be entered so that the variables can be addressed. The required numbers can be found in the
NC variables documentation.
References:
Lists sl (Book1); Variables
By entering a zero (0) as the block number or the line or column index, it is possible to use the variable in the S7
PLC as a pointer to these data. When reading or writing these data via the functions "PUT" and "GET", the
optional parameters "UnitX", "ColumnX" and "LineX" must be filled with the necessary information.
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
P3: Basic PLC Program for SINUMERIK 840D sl
13.12 Basic conditions and NC VAR selector
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