The 6ES7952-1KP00 is an 8 MB Flash EPROM memory card for SIMATIC S7-400 controllers. It is the practical midpoint in the S7-400 FEPROM lineup — double the capacity of the 4 MB card, half the 16 MB card. For the majority of machine-level automation projects, 8 MB holds the user program, hardware configuration, function blocks, and data structures with room to spare. Like every FEPROM card in the S7-400 family, it is non-volatile — no backup battery, no data loss on power failure, automatic program reload on every power-up.

When does 8 MB make sense over 4 MB or 16 MB?

Choose 8 MB when your STEP 7 project exceeds 4 MB but does not approach the 16 MB threshold. This is common in machines with a moderate number of function blocks, multiple data block instances, and a small recipe database. The 8 MB card provides comfortable headroom without paying for capacity you will never use. If your project is at or near 4 MB today, the 8 MB card also gives you room to grow as the machine accumulates features across its service life.

Do I need a battery for this card?

No — and that is the defining advantage of FEPROM over RAM. The 6ES7952-1KP00 uses Flash EPROM technology, which is inherently non-volatile. Remove the card from the CPU, store it on a shelf for years, reinsert it — the program is intact. This eliminates the backup battery as a failure point and a maintenance item. The tradeoff is that FEPROM cards require the CPU to be in STOP mode for program downloads, whereas RAM cards support RUN-mode downloads.

Frequently Asked Questions

Can I upgrade from a 4 MB FEPROM card to this 8 MB card in an existing machine?

Yes. Power down the CPU, swap the cards, place the CPU in STOP, and download the program to the new card via STEP 7. The S7-400 will recognize the larger capacity automatically.

Does this card support the S7-400H high-availability system?

Yes. Each CPU in an H-system redundant pair requires its own FEPROM card. Both CPUs can use the 8 MB card independently.