CPU 226 – what bolts straight in
The 6ES7216-2BF21-0XB0: Inputs are source/sink per group, configurable. Accepts 2-wire sensors. Threshold: signal '0' from 0 to 5 V, signal '1' from 15 V up. That's 24 V logic – fits most field devices.
Backup and retention
Program stores on integral EEPROM – no battery needed to hold the code. Current DB values stay in RAM, retentive via high-performance capacitor: 190 hours backup at 40 °C, 200 days with optional battery module. Enough to ride a long outage.
High-speed and counting
Six high-speed counters, each 30 kHz, 32-bit. Use as up/down counters or connect two incremental encoders at 20 kHz (A/B mode). Parameterizable enable/reset inputs. Interrupt on setpoint – call any subroutine. Good for fast position or flow pulses. Timers cover 1 ms to 54 minutes. Four fast timers (1 ms–30 s), sixteen medium (10 ms–5 min), 236 slow (100 ms–54 min). All the ranges you need for a process line.