The 6ES7954-8LC04 is a 4 MB Flash-EPROM memory card for SIMATIC S7-1200 and S7-1500 controllers — the smallest-capacity and highest-endurance card in the S7-1x00 family. It is rated for a minimum of 500,000 write/delete cycles, with data retention of up to 10 years when cumulative writes stay under 50,000. Physically identical to every other S7-1x00 card at 24 × 32 × 2.1 mm and roughly 3 grams. It is the current production version, succeeding the 6ES7954-8LC03-0AA0.

Who still needs a 4 MB card?

OEMs shipping a standard, well-established program across hundreds of identical machines. Engineers running compact work cells where the compiled program, hardware configuration, and recipe data fit comfortably within 4 MB. In these applications, the 4 MB card is not a compromise — it is the best choice. It delivers five times the write endurance of a 2 GB card and is the most cost-effective entry point in the S7-1x00 memory card line. If your machine runs a mature program that does not grow, this card will likely outlast the PLC it is plugged into.

What changed from the 6ES7954-8LC03 to the 8LC04?

An article number update — nothing functional. Same 4 MB capacity, same 500,000-cycle endurance, same 3.3V Flash-EPROM, same dimensions. Siemens changed the suffix from -8LC03 to -8LC04 for internal manufacturing tracking reasons. The 8LC03 is discontinued and all new 4 MB card orders are automatically fulfilled with the 8LC04.

Frequently Asked Questions

Can a 4 MB card run out of space on an S7-1500?

It depends on your project. An S7-1500 program with extensive HMI data, motion control libraries, and safety programs can exceed 4 MB. Check your compiled project size in TIA Portal before ordering. If your project exceeds 4 MB, step up to the 12 MB card (6ES7954-8LE04) which shares the same 500,000-cycle endurance, or the 256 MB card (6ES7954-8LL04) if you need more room and can accept 200,000-cycle endurance.

Is this card compatible with older S7-1200 firmware?

Yes. The small-capacity cards have the broadest firmware compatibility across the S7-1200 range — they work with firmware versions dating back to the earliest S7-1200 releases.