Siemens 6Es5948-3Ur21 CPU Module

Siemens 6ES5948-3UR21 is the CPU948R central processing unit for the SIMATIC S5-155H controller, delivering 1,664 KB of RAM to support user programs and data. This CPU module is designed for the Siemens S5 family and functions as the system’s main processing element in S5-155H configurations. It includes a 20 mA current-loop TTY interface for OP/PG/PC access and a dedicated memory-submodule interface for program storage via Flash EPROM. The 6ES5948-3UR21 variant specifies the CPU 948R within the S5-155H lineup and uses a double-width form factor compatible with the S5 rack architecture. When paired with the matching memory submodule and interface components, it forms a complete CPU assembly for legacy Siemens automation installations, handling execution of the control logic and data handling while communicating with I/O modules over the S5 bus. Commonly encountered in refurbished or surplus inventories, this CPU module is documented in Siemens references and distributor catalogs as the central processing unit for S5-155H systems, making it a viable option for maintenance or expansion of existing S5-155H-based plants.