CPU 1518HF — 32 kB I/O image, PROFIsafe, MRP ring manager
The Siemens 6ES7518-4JP00-0AB0 is a CPU 1518HF designed for high-availability and fail-safe applications. It supports PROFIsafe V2.4 / V2.6 for safety-oriented communication and acts as an MRP Automanager per IEC 62439-2 Edition 2.0 for media redundancy in ring topologies. The CPU provides a 32 kbyte input process image and a 32 kbyte output process image, meaning all I/O data for a typical mid-sized safety application fits within the process image without needing direct peripheral access.
Programming languages and failsafe capability
The CPU supports LAD (ladder diagram) and FBD (function block diagram) including failsafe variants, plus SCL, STL, and GRAPH for structured and sequential control. This covers both standard logic and safety-related code in the same engineering environment. Forcing is supported for standard variables but not for fail-safe variables, which is consistent with safety integrity requirements — forcing a safety output would break the SIL loop.
Network interfaces and protocol support
The CPU has a 100 Mbps Ethernet interface and a second X3 interface capable of 1000 Mbps. It supports TCP/IP, UDP, MODBUS TCP, LLDP, SNMP, and I&M data (I&M0 to I&M3). IRT and MRPD are not supported, so this CPU is not intended for isochronous motion control applications. DCP and DNS are supported for device configuration and network naming; DHCP and HTTP/HTTPS are not. This means the CPU is configured via the engineering tool (TIA Portal) using its MAC address or assigned name, not via a web browser.
Environmental range and physical dimensions
Dimensions are 210 mm wide, 147 mm high, and 129 mm deep.