Memory concept

All CPUs of S7-400 feature two types of memory. This subdivision of work memory increases performance by 100%. Where a standard processor accesses its RAM at least twice, the S7-400 special processor accesses the code memory and data memory simultaneously in one cycle. There are also separate code and data buses for this purpose. The size of the work memory is determined by the appropriate CPU selected from the finely graded CPU spectrum.

For small and medium programs, the integral load memory (RAM) is sufficient. For larger programs, the load memory can be increased by inserting memory cards. Plug-in flash memory cards are available for retentive storage without the need for a battery.

Block encryption

The functions (FCs) and function blocks (FBs) can be stored in the CPU in encrypted form to protect the know-how of the application.