Siemens SIMATIC S7-200 System Manual page 391

Allocating Memory
The Data Log Wizard creates a block in the V memory area of the PLC. This block is the memory
address where a data log record will be constructed before it is written to the memory cartridge.
You specify a starting V memory address where you want the configuration to be placed. You can
either select the V memory address or let the Data Log wizard suggest the address of an unused
V memory block of the correct size. The size of the block varies based on the specific choices you
have made in the Data Log wizard. See Figure 14-5.
To allocate memory, follow the steps
below:
1. To select the V memory address
where the data log record will be
constructed, click in the Suggested
Address area and enter the
address.
2. To let the Data Log Wizard select
an unused V memory block of the
correct size, click the Suggest
Address button.
3. Click the Next button.
Project Components
The project components screen lists the
different components that will be added
to your project. See Figure 14-6.
Click Finish to complete the Data Log
Wizard and add these components.
Each data log configuration can be given
a unique name. This name will be shown
in the project tree with each wizard
configuration. The data log definition
(DATx) will be appended to the end of
this name.
Using the Symbol Table
A symbol table is created for each data
log configuration. Each table defines
constant values that represent each data
log. These symbols can be used as
parameters for the DATx_WRITE
instructions.
Each table also creates symbol names
for each field of the data log. You can
use these symbols to access the values use these symbols to access the values
of the data log in V memory.
Using Data Logs
Figure 14-5 Allocating Memory
Figure 14-6 Project Components
Figure 14-7 Symbol Table
Chapter 14
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