CPU 318-3FL01-0AB0 — SFB with PROFIsafe and IRT
The Siemens 6ES7318-3FL01-0AB0 is a SIMATIC S7-300 CPU 318 SFB (Safety Fault-Proof) unit designed for fail-safe automation. It carries FM 8 (8 function blocks) and supports CFC, FBD, LAD, SCL, STL, GRAPH, and HiGraph programming, all under STEP 7 V5.5 or higher. The integrated PROFINET interface enables IRT (isochronous real-time) communication — critical for synchronized motion axes — and UDP/TCP/IP with loadable function blocks. PROFIsafe is supported natively, meaning this CPU can run safety programs (up to SIL 3) over the same PROFINET cable as standard control, without a separate safety bus.
I/O capacity and communication
The CPU handles 244 bytes of process input and 244 bytes of output data, with a maximum of 32 modules overall. It includes 4 counters (preset 10) and supports forcing, retentive memory (must be restarted at each restart), and routing. Communication interfaces include RS 485, PROFINET (client/server), and up to 4 CP connections for LAN, 10 for PtP, and 8 for additional PROFIBUS via CP. No MPI or DPV1 is available — plan your network topology accordingly. The GSD file is available from Siemens for PROFIBUS integration.
Physical and environmental
Dimensions are 120 mm wide × 125 mm high × 130 mm deep. Operating temperature range is 0 °C to 60 °C. The I2t rating is 1.2 A²·s, and the CPU is isolated. It mounts on a standard DIN rail in a control cabinet — no special cooling required within the rated range.