What this CPU is
The 6AG1516-3FN02-2AB0: It supports MRP (Media Redundancy Protocol) as Automanager, Manager, or Client per IEC 62439-2 Ed 2.0, handling up to 50 devices in the ring. MRPD is also available, though it requires IRT frames — note that the CPU itself does not support IRT natively, so MRPD is only functional when a separate IRT-capable device is on the line. Programming languages include LAD, FBD, and SCL, with failsafe logic blocks integrated into both LAD and FBD editors. PROFIsafe is built in, so safety-oriented process data can be mapped without a separate safety module.
Key specs and what they mean for your BOM
Process image size is 32 kbyte for both inputs and outputs — comfortable for a medium-sized line but not a large distributed system. If your application exceeds that, you will need to offload to distributed I/O via PROFINET or PROFIBUS. The I²t rating is 0.02 A²·s. DCP (Discovery and Configuration Protocol) is supported, so the CPU can be detected and assigned an IP address via the Siemens tool chain without a separate memory card or DIP switches. MODBUS TCP is also available for integration with third-party HMIs or SCADAs. Up to 8 communication modules (CMs/CPs) can be inserted for additional PROFIBUS, PROFINET, or Ethernet interfaces. That leaves room for expansion beyond the onboard PROFIBUS and PROFINET ports.
Comparing to the -01 revision (6AG1516-3FN01-2AB0)
Supports MRP Automanager per IEC 62439-2 Edition 2.0 for up to 50 devices. IRT not supported; dimensions 70 x 147 x 129 mm.