The 6ES7511-1FK02-0AB0: This Siemens CPU 1211C packs failsafe FBD programming and PROFIsafe into a 35 mm wide brick — no separate safety PLC needed for SIL-rated lines. It runs MRP as redundancy manager (up to 50 devices in the ring), so you can loop PROFINET without an extra switch module. The 32 kB I/O image handles a couple of remote racks, and the -40 to 70 °C range means it won't flake in an unheated warehouse. Firmware revision -FK02 is the current drop; the -FK01 predecessor shares the same mechanical footprint but lacks some software optimizations.
Field-fit notes
DIN-rail mount, 35 mm wide, 147 mm tall, 129 mm deep. DCP enables device configuration; FBD with failsafe allows safety logic; forcing limited to non-fail-safe signals. I/O mapping is straightforward: 32 kB input and output process images. All four CM/CP slots populate via the side bus; max four comm modules total (PROFIBUS, PROFINET, Ethernet). For MODBUS TCP, it's built-in — no extra card needed.