Siemens 6ES5155-3UA11 is a SIMATIC S5-155U central controller rack designed to host CPU and I/O modules in legacy S5 PLC systems. This 21-slot chassis is sold without a power supply, meaning it is used with a separate power module to power the installed cards. As part of the 155U family, it provides the modular backbone for automation tasks in older plants relying on Siemens S5 technology.
