The Siemens 6ES5 308-3UC21 Simatic interface module serves as the IM 308-C for S5-115U, S5-135U, and S5-155U programmable controllers. It connects the central rack to expansion units or distributed I/O stations over the S5 bus, supporting data exchange for input/output modules in larger automation configurations. The module occupies one slot in the PLC rack and operates on the 5 V DC supply provided by the backplane, maintaining compatibility with legacy Simatic S5 installations in industrial control systems.
