Failsafe CPU with PROFIsafe V2.4/V2.6
The Siemens 6ES7518-4FP00-3AB0 is a CPU 1518F-4 PN/DP combining standard and failsafe logic on one controller. It supports FBD and LAD programming including failsafe blocks, and runs PROFIsafe V2.4 or V2.6 for safety-related communication over PROFINET. The process image is 32 kbyte for inputs and 32 kbyte for outputs, which sets the deterministic I/O data volume per bus cycle. This is the ceiling for the number of fast I/O points you can map without additional backplane communication.
PROFINET with MRP and 1 Gbps uplink
The CPU has three PROFINET ports: two at 100 Mbps for ring or line topology, and one dedicated X3 interface that supports 1000 Mbps for high-speed uplink to a plant network or SCADA server. MRP is supported with the CPU acting as Automanager per IEC 62439-2 Edition 2.0, Manager, or Client — no external switch needed for ring redundancy. IRT is not available on this CPU, so deterministic motion control over PROFINET is not possible. For applications requiring isochronous real-time, the CPU 1518-4 PN/DP (non-F variant) is the correct choice.
Extended temperature and RS-485 interface
The RS-485 interface on X4 supports Modbus RTU or point-to-point communication, useful for connecting legacy drives or remote I/O without an additional communication module. Up to eight communication modules (CMs or CPs) can be inserted for PROFIBUS, additional PROFINET, or Ethernet networks. The hardware clock maintains time across power cycles, and I&M data (I&M0 to I&M3) is supported for asset management.
Integrated PID and web server
Two integrated PID controllers are available: with optimisation for temperature loops, and for valve positioning. The CPU also hosts a web server with standard and user-defined pages accessible via HTTP and HTTPS, plus SNMP for network monitoring.