The Siemens 6ES7288-1CR40-0AA0 is an S7-200 SMART CPU with a 120/230 V AC supply, 12 kbyte program memory, and 32-byte digital I/O map. It supports LAD, FBD, and STL programming, includes a real-time clock with 7-day backup, and runs up to 8 PID loops. The RS485 port (max 187.5 kbps) handles Modbus RTU or USS drives, and the Ethernet port supports TCP/IP with auto-negotiation and autocrossing.
Supply and I/O fit
Rated 24 V DC for the logic supply, but the main power input accepts 120 V AC or 230 V AC — transformer-isolated at 1,500 V AC. That makes it a direct fit for panels with an existing control transformer, no separate 24 V DC supply needed for the CPU itself. The 32-byte input and 32-byte output maps are fixed; forcing is supported for commissioning. Digital input thresholds: signal '0' below 5 V DC, signal '1' from +15 to +30 V DC. That's standard 24 V DC sinking logic — compatible with most three-wire sensors and pushbuttons without level shifting.