The 6ES7954-8LT04 is a 32 GB industrial Flash-EPROM memory card for SIMATIC S7-1200 and S7-1500 controllers — the largest capacity available in the S7-1x00 memory card family. At 24 × 32 × 2.1 mm and roughly 3 grams, it fits directly into the memory card slot of any S7-1200 or S7-1500 CPU and provides non-volatile storage for programs, data logs, recipes, and firmware.

How does capacity affect write endurance?

Higher-capacity SIMATIC S7 memory cards use denser NAND flash cells, which trade write endurance for storage. The 32 GB card is rated for a minimum of 100,000 write/delete cycles, with data retention of up to 10 years when write cycles stay under approximately 10,000. At the other end of the range, the 4 MB card offers 500,000 cycles. If your application writes frequently — such as continuous data logging — consider a smaller, higher-endurance card. If your priority is storing large programs and archives that change infrequently, the 32 GB card is the right choice.

Should I order the 6ES7954-8LT04 or the 6ES7954-8LT03?

The 6ES7954-8LT04 is the current production version. The 6ES7954-8LT03 was its predecessor and is now discontinued — Siemens will automatically convert 8LT03 orders to the 8LT04 once remaining stock is exhausted. The two cards are functionally identical: same 32 GB capacity, same 3.3V Flash-EPROM technology, same physical dimensions. Order the 8LT04 for any new project. The 8LT03 is only necessary if your existing machine bill of materials specifies that exact legacy part number for a like-for-like replacement.

Frequently Asked Questions

Can I use a 32 GB card in an S7-1200 CPU?

Yes. All S7-1200 firmware versions V4.0 and later support the full 32 GB capacity. Earlier firmware versions may not recognize capacities above 2 GB — check your CPU's firmware version before ordering.

Does filling the card affect read or write performance?

No. Flash-EPROM read speed is independent of how full the card is. Write endurance is managed per memory block — filling the card to capacity does not accelerate wear on already-written blocks.