Memory card for S7-300 / C7 / ET 200
The Siemens 6ES7953-8LJ20-0AA0 is a spare-part Micro Memory Card (MMC) for SIMATIC S7-300, C7, and ET 200 systems. It provides 512 KB of 3.3 V Nflash storage, enough for the program and data blocks of a mid-range S7-300 CPU. This is the P. variant of the MMC, meaning it supports the CPUs that require a plug-in memory card for program storage — no battery backup needed, since the Nflash retains data without power.
Compatible with all CPUs that accept an MMC (including the ET 200S and ET 200pro CPUs with an MMC slot). The card inserts into the slot on the CPU front panel; the CPU powers the card directly from the backplane bus.