The 6ES7952-1KK00 is a 1 MB Flash EPROM memory card for SIMATIC S7-400 controllers — the smallest capacity in the S7-400 FEPROM family. It is built for the simplest, most stable S7-400 programs: a single focused control task, minimal data overhead, a code base that has not changed in years. At 1 MB, you get the full non-volatile benefit of Flash EPROM — no battery, no data loss, automatic program reload on every power-up — in the most economical FEPROM package available for the platform.

Is 1 MB really enough for an S7-400?

Yes — for the right application. Many S7-400 controllers in the field run compact programs on machines that were commissioned years or decades ago. A pump control station, a simple material handling cell, a filter press, a valve sequencing system — these applications often compile to well under 1 MB. If your program fits, paying for more capacity adds nothing. The 1 MB card is not a compromise; it is exactly the right tool for a well-defined, long-stable automation task.

When should I consider stepping up from 1 MB?

Two reasons. First, if your STEP 7 compiled project size is close to 1 MB today, give yourself headroom with the 2 MB card (6ES7952-1KL00) — programs tend to grow over a machine's service life as features and data points accumulate. Second, if you are starting a new project where the final program size is uncertain, the 2 MB or 4 MB card provides a safer margin. The 1 MB card is ideal when you know exactly what your program needs and it fits.

Frequently Asked Questions

How many function blocks fit in 1 MB?

There is no fixed count — it depends on the complexity of each block. As a rough guide, a lean S7-400 program with 50–100 standard function blocks, hardware configuration, and associated data blocks typically compiles well under 1 MB. Check your actual compiled size in STEP 7 project properties for a definitive answer.

Does this card expire or degrade over time?

No. Flash EPROM is non-volatile solid-state storage. The data retention is measured in decades under normal operating conditions. There is no battery to deplete and no moving parts to wear out. The card itself is rated for the full operating life of the S7-400 system.