CPU 314 IFM — 32 KB working memory with integrated I/O
The Siemens 6ES7314-5AE83-0AB0 is a SIMATIC S7-300 CPU 314 IFM with 32 KB integrated working memory, which holds roughly 10 K instructions at 3 bytes per instruction. This is the memory budget for your application code and data blocks — enough for medium-scale logic, PID loops, and motion sequences on a single controller. It supports MPI communication as a server, so it can exchange data with other S7-300 CPUs, operator panels, or a programming device over the built-in MPI port without an extra CP module. The FM 4 designation means the CPU includes four integrated function blocks for counting, positioning, or cam control — useful for handling incremental encoders or simple axis control directly on the CPU without a separate FM module.
Memory, scan time, and programming scope
Working memory is 32 KB integrated RAM, with a maximum load memory of 8 KB. Retentive data (144 bytes of bit memories, counters, timers, and data) is maintained without a battery; with a battery fitted, all blocks are retained. Cycle time is adjustable from 1 ms to 6000 ms, with a preset of 150 ms. The command set covers binary logic, bracketed operations, fixed and floating-point arithmetic, jump functions, and block calls — enough for structured programming in LAD, FBD, STL, or SCL. Nesting depth is 8 levels, and the CPU supports GRAPH sequential control and PID closed-loop control with function blocks for continuous or binary controller outputs, setpoint limitation, and auto/manual mode.
I/O addressing and wiring
The CPU addresses 122 bytes of inputs and 122 bytes of outputs. Digital inputs accept 2-wire sensors and signal thresholds of -3 to +5 V for signal '0' and +15 to +30 V for signal '1', plus analog inputs from -10 V to +10 V. Maximum shielded cable length is 1000 m. The CPU supports up to 128 digital channels and includes a 256-byte maximum number for diagnostics or data logging. Communication expansion includes one slot for a CP 342-5 PROFIBUS module, one slot for an industrial Ethernet CP or LAN module, and two slots for PtP (point-to-point) CPs — covering serial or fieldbus connectivity without overloading the backplane.
Environmental range and physical fit
Rated for -25 °C to +60 °C ambient, this CPU handles unheated enclosures or warm cabinet environments without forced cooling. The 160 mm width, 125 mm height, and 130 mm depth fit a standard S7-300 mounting rail — allow for the front connector and cable duct in your panel layout.