Siemens NAN 67 Series Wartungshandbuch PDF herunterladen (Seite 57)

4-5

Ladder Logic (LAD) for S7-300 and S7-400

C79000-G7076-C504-02

4.3 Editing the Declaration Table

When you create single shared data blocks or UDTs, you must declare their

elements (variables) and their data types. For this you use the declaration

table in the declaration view. When working with data blocks, you change to

this view with the menu command View

Declaration View.

This does not apply to data blocks assigned to a UDT or FB since the

declaration is already defined by the UDT or FB.

The declaration view of a data block shows the addresses, the declaration

types (only for instance DBs), the variable names (symbols), initial values

and comments. Figure 4-3 shows an example:

DB15 - <Offline>

Address Symbol Data Type Initial Value Comment

speed

runtime

motor_on

STRUCT

INT

DINT

BOOL

100

L#0

0.0

+0.0

+2.0

+6.0

+10.0

history REAL

motor_off BOOL+10.1

END_STRUCT

FALSE

=12.0

0.000000e+000

FALSE

Maximum RPM

Figure 4-3 Declaring a Data Block

The columns have the same significance as those in the declaration table for

logic blocks (see Section 3.3).

To enter a new declaration, type in the required declaration type, variable

name, data type, initial value (optional) and comment (optional). You can

move the cursor from one cell to the next using the

TAB or RETURN keys. At

the end of each row, an address is allocated to the variable.

The syntax is checked after each cell has been edited and errors are shown in

red. You can continue to make your entries and correct any errors later.

Note

Editing in the declaration view is the same as editing the variable declaration

table of logic blocks (see Section 3.4). The editing and input procedures are

identical and you should also proceed in the same way when entering arrays

or structures.

Purpose of the

Declaration View

Structure of the

Table in the

Declaration View

Procedure

Creating Data Blocks and User-Defined Data Types

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