Overview
The CPU 1517H-3 PN is a Siemens SIMATIC S7-1500H-series PLC processor, order code 6ES7517-3HP00-0AB0, supporting DNS and carrying a single PROFINET port with MRP Automanager per IEC 62439-2 Edition 2.0.
As the central controller in a redundant S7-1500H station, the 6ES7517-3HP00-0AB0 executes user logic and synchronises with a paired CPU over the PROFINET ring. The MRP Automanager function handles media redundancy automatically — if a cable fault opens the ring, the controller reconfigures the topology within the configured update time, which itself depends on the communication share, number of IO devices and quantity of configured user data. The single PROFINET port runs at 100 Mbps and carries both process data and programming traffic. MODBUS TCP is supported natively, so the CPU can talk to drives, HMIs and third-party controllers without an additional gateway. IPv4 is the only IP protocol on this unit; DHCP and HTTP are not available, but LLDP and SNMP are present for network management and topology discovery.
I/O & memory architecture
The process image is fixed at 32 kbyte for inputs and 32 kbyte for outputs — all I/O data lives in the process image, so no separate addressing of peripheral areas is needed for standard modules. The module size is 16 kbyte, which governs the address space consumed on the backplane. Program and data memory reside on the SIMATIC memory card, which can be up to 32 Gbyte. This is the figure that sizes the application: a large machine with extensive recipe management, data logging and visualisation archives will need a card at the upper end of that range. The CPU supports LAD, FBD, SCL and STL programming languages, plus a PID controller with integrated optimisation for temperature loops.