Technical data

Downloading and Uploading
19.1 Downloading from the PG/PC to the Programmable Controller
Programming with STEP 7
418 Manual, 05/2010, A5E02789666-01
19.1.3 Load Memory and Work Memory in the CPU
After completing the configuration, parameter assignment, and program creation and establishing
the online connection, you can download complete user programs or individual blocks to a
programmable controller. To test individual blocks, you must download at least one organization
block (OB) and the function blocks (FB) and functions (FC) called in the OB and the data blocks
(DB) used. To download the system data created when the hardware was configured, the networks
configured, and the connection table created to the programmable controller, you download the
object "System Data".
You download user programs to a programmable controller using the SIMATIC Manager, for
example, during the end phase of the program testing or to run the finished user program.
Relationship - Load Memory and Work Memory
The complete user program is downloaded to the load memory; the parts relevant to program
execution are also loaded into the work memory.
CPU Load Memory
• The load memory is used to store the user program without the symbol table and the
comments (these remain in the memory of the programming device).
• Blocks that are not marked as required for startup will be stored only in the load memory.
• The load memory can either be RAM, ROM, or EPROM memory, depending on the
programmable controller.
• The load memory can also have an integrated EEPROM part as well as an integrated RAM
part (for example, CPU 312 IFM and CPU 314 IFM).
• In S7-400, it is imperative that you use a memory card (RAM or EEPROM) to extend the load
memory.