What it is and what the key specs mean
The Siemens 6AG1317-6FF04-2AB0 is an S7-300 CPU module with firmware version 8 (FM 8), supporting CFC, FBD, LAD, SCL, STL, GRAPH, and HiGraph® programming. The FM 8 designation means it requires STEP 7 V5.5 + SP1 or higher (or V5.3 + SP2 with HSP 203) for configuration — a key constraint if your installed base runs older TIA Portal versions. CFC capability allows continuous function chart programming, useful for process control sequences that need data-flow-style logic. The I²t rating of 1 A²·s indicates the backplane current draw; verify your power supply has headroom for this module plus others in the rack. The CPU provides 244 bytes of inputs and 244 bytes of outputs, with 32 overall diagnostic interrupts and forcing capability for commissioning.
Sourcing and fit for legacy installs
Mounting dimensions are standard S7-300: 40 mm wide, 125 mm high, 130 mm deep. The module snaps onto the DIN rail without glands, and the 40 mm width preserves slot pitch for adjacent modules.
Integration notes
Communication options include RS 485 (PROFIBUS MPI possible via CP), and routing is active only when the interface is active. GSD files for PROFIBUS are available on the Siemens FTP site. The module can act as both a PROFINET client (via CP and loadable FB) and server, though PROFIsafe is not supported. For safety-rated applications, keep this CPU separate from the safety chain. Retentive data must be restarted at each restart; plan for a routine memory re-initialization after power cycles.