Power, retention and the handover envelope
Power it up and prove it: the CPU accepts a 24 V supply across 15.4 to 28.8 V, with the same rail used for the integrated 24 V sensor/source output rated up to 3.75 A both up to 40 °C and up to 55 °C, and a typical power loss of 8 W that the panel thermal budget has to absorb. Retention runs on a high-performance capacitor as standard, backed by an optional battery module — the spec puts backup time at 100 h minimum (≥ 70 h at 40 °C) on the capacitor and around 200 days typical with the battery, which is the figure to write into the handover sheet so the maintenance crew knows when DB1 data and retentive bits will start to drift if the battery is missed.
Inputs, outputs and the high-speed edge
Source/sink selection is per group, which lets the wireman follow the cabinet drawing's existing convention rather than re-terminate for a fixed polarity.
Comms, lengths and the wiring practice
The onboard port is an integrated RS-485, usable as an MPI slave for data exchange with S7-300/S7-400 CPUs, OPs, TDs and Push Button Panels at 19.2 or 187.5 kbit/s, and as PPI for program functions, HMI functions (TD 200, OP) and S7-200-internal CPU-to-CPU traffic at 9.6, 19.2 or 187.5 kbit/s. Cable runs follow the usual S7-200 rules: shielded segment up to 500 m at the lower PPI/MPI rates, unshielded segment up to 150 m — these are the limits to write on the cable schedule, not the generic Cat-5 numbers. Program execution is free-cycle OB 1 with time-controlled interrupt at 1 to 255 ms, and the timer stack covers 1 ms to 54 min (with 4 fast timers at 1 ms to 30 s, 16 timers at 10 ms to 5 min and the remainder at 100 ms to 54 min), which matches the standard S7-200 instruction set the existing code is likely written against.