What this is and where it lives
This is the Siemens SIPART PS2, order code 6DR5020-0EG10-0AA0. It's a version 0 unit – 2-wire 4-20 mA input, no HART – built for double-acting actuators. Out here in the grease, you want something that survives washdowns and stays sealed; this one's rated IP66 per IEC/EN 60529 and NEMA 4X, so it takes a hose-down without flinching.
Drive side
Double-acting means it controls both ports of the actuator – extend and retract. That covers spring-return and double-acting valves. If your application needs a fail-position, this is the one.