The Siemens 6ES7138-4CA01-1AA0 is a PM-E power module for the ET 200S distributed I/O system, delivering 24 V DC to the module bus with integrated diagnostics. It ships as a 5-unit packing unit — a spare-part bundle for maintaining existing ET 200S racks rather than a new-design component. At 15 mm wide, it occupies a single slot on the ET 200S rail; the 52 mm depth and 81 mm height match the standard ET 200S module footprint, so it drops into an existing populated rack without re-laying out the cabinet.
Sourcing reality for a current spare part
As a spare-part item sold in a 5-pack, it is typically sourced against a BOM line for an existing ET 200S node rather than for new greenfield designs.