The 6ES7952-1KT00 is a 32 MB Flash EPROM memory card for SIMATIC S7-400 controllers. It stores the user program, hardware configuration, and data blocks in non-volatile 5V Flash EPROM — no backup battery needed. On every CPU power-up, the program is automatically loaded from the card into the CPU's work memory. The card's load memory is independent of the CPU's integrated memory, functioning as a removable, shelf-stable program archive inside the PLC.

What is the difference between the 32 MB and the 64 MB card?

Capacity — nothing else. Both the 6ES7952-1KT00 (32 MB) and the 6ES7952-1KY00 (64 MB) share the same 5V Flash EPROM technology, long-design form factor, non-volatile operation, and S7-400 compatibility. For most discrete manufacturing applications, 32 MB is ample. Large process automation projects with thousands of data points, extensive recipe databases, or integrated HMI data structures may benefit from the 64 MB card. If your project fits within 32 MB, the 1KT00 is the more economical choice.

RAM card or FEPROM card — which one does my S7-400 need?

FEPROM cards — including this 6ES7952-1KT00 — are non-volatile. They retain the program through power cycles without a battery and are the standard choice for most S7-400 applications. RAM cards offer faster write speeds and support runtime writes to load memory (for example, updating recipe data directly on the card during operation). However, RAM cards require a backup battery to survive a power cycle. If your application does not write to load memory at runtime, the FEPROM card is the simpler, lower-maintenance option.

Frequently Asked Questions

Does this card work with the S7-400H redundant CPU?

Yes. FEPROM cards are supported across the S7-400H high-availability CPU range. Each CPU in a redundant pair requires its own memory card — the two cards do not share data between controllers.

Can I transfer a program between S7-400 CPUs using this card?

Yes. Write the program to the card from the source CPU or a programming device, then insert the card into the target CPU. On the next power-up, the S7-400 will detect the program and copy it to work memory automatically.