CPU 314 with 248 I/O and FM 8
The Siemens 6ES7314-6CF00-0AB0 is a CPU 314 for the SIMATIC S7-300 family, carrying 248 digital inputs and 124 digital outputs — enough I/O for a medium-sized machine or process skid without needing an expansion rack. It supports FM 8 function blocks, plus CFC, FBD, LAD, SCL, STL, and GRAPH programming languages, so the same CPU handles sequential logic, continuous function charts, and structured text for data handling.
Memory, racks, and fieldbus
Work memory maxes at 16 kbyte — enough for a mid-size application, but tight for large data blocks or extensive SCL routines. The CPU supports up to 4 racks, giving room for signal modules and function modules in a distributed chassis. An integrated DP interface handles PROFIBUS DP communication without a separate CP, and the CPU supports SYNC/FREEZE for time-synchronous input capture. The CPU is not expandable — no additional memory cards or second processor slot. It fits a 120 mm wide, 125 mm deep, 130 mm high footprint, standard for S7-300 single-width modules. The backplane connector is keyed to the rack; the CPU auto-negotiates the bus cycle time on insertion.
Programming and analog handling
Programming requires STEP 7 V5.1 SP2 or later — the CPU does not support TIA Portal natively. It reads Pt 100 RTDs directly via the integrated analog inputs, and handles 0 to 10 V, 0 to 20 mA, and resistance signals. The adjustable input filter (T 0 to T 255) lets you debounce noisy field signals before they hit the logic. The CPU includes an RS 485 interface for point-to-point or multi-drop connections, and supports up to 4 PtP CPs and 2 LAN CPs via the backplane. Current and voltage measurement are isolated from the backplane bus, so a field-side fault won't take down the rack.
The 6ES7314-6CF00-0AB0 is an established S7-300 CPU — no official lifecycle status or successor is recorded in the evidence. For a BOM freeze or line-down replacement, confirm the rack slot and the STEP 7 version before committing.