What the extended temperature range buys you
The 6AG1952-1AY00-7AA0 is the SIPLUS ruggedized version of the standard S7-400 RAM card, built on the 6ES7952-1AY00-0AA0 base design with conformal coating applied per IPC-CC-830A Class A. That coating is the difference between a card that survives in a climate-controlled electrical room and one that holds the unit on the grid in a turbine hall where the ambient climbs past 50 °C.
Memory sizing and compatibility
64 MB of RAM, no flash retention on power loss — this is a load-memory card for the S7-400 rack, not a permanent program store. The CPU loads the user program and data blocks from this card into its internal RAM at startup; on power cycle the card contents are lost unless the program is also held on the CPU's own memory card or an EPROM card. Belongs to the S7-400 product family, so it fits the long-design memory-card slot on any S7-400 CPU or CP that accepts the standard RAM card format. The 64 MB capacity is sufficient for mid-range S7-400 applications — a large recipe database or a multi-axis motion program will push against that ceiling, and you would step up to the 128 MB or 256 MB variants if the project calls for it.
Environmental and altitude derating
The -25 °C to +70 °C range is the full operating envelope at sea level. At altitude the upper limit derates: above 2 000 m the maximum allowed temperature drops by 10 K per 1 500 m increment, so at 3 500 m the card is good to 60 °C, and at 5 000 m it is good to 50 °C. The lower limit stays at -25 °C across the full altitude range. The conformal coating also qualifies the card for ANSI/ISA-71.04 GX group A/B environments — hydrogen sulfide, chlorine, and other corrosive gases up to EN 60721-3-3 class 3C4 limits — plus salt spray and oil exposure. That makes it a candidate for offshore platforms, chemical plants, and paper mills where the standard card would fail from creep corrosion inside two years.