Power and supply
The 6ES7212-1BB22-0XB0: Supply range is 20.4 V to 28.8 V DC, so it'll hold through a saggy 24 V bus. The 7 W loss is modest — no derating worries in a standard cabinet, but count it in the power budget if you're packing multiple modules. Backup for program and data is handled by an integral EEPROM (no battery needed for storage). The high-performance capacitor holds retentive data for at least 8 hours at 40 °C, or 200 days typ. with the optional battery module.
Communications and programming
The single RS-485 port serves both MPI (slave) and PPI protocols. Maximum cable length is 500 m shielded, 150 m unshielded. That's enough for a small line; for longer drops you'd need a repeater or a different CPU with a second port. Programming languages: LAD, FBD, and STL are all supported. The instruction set covers bit logic, timers (1 ms to 54 min), counters (4 high-speed up to 30 kHz), integer and floating-point math, and interrupt processing.