The Siemens 6DR5120-0NN01-0AA4 is a SIPART PS2 electropneumatic positioner in a glass-fiber reinforced polycarbonate Makrolon enclosure, IP66 rated per IEC/EN 60529 and NEMA 4X. This variant is a 2-wire 4-20 mA loop-powered unit with HART communication, designed for double-acting actuators. It ships with a position feedback module providing a 4-20 mA output and a mounted pressure gauge block (aluminum, double-acting, ¼-18 NPT, scaled in MPa and psi). The electrical connection is ½-14 NPT; pneumatic connections are ¼-18 NPT. No explosion protection is included; this is a general-purpose unit.
Double-acting means it drives actuators with two pneumatic ports — supply to open, supply to close. If your valve actuator is spring-return (single-acting), the single-acting sibling 6DR5010-0NG01-0AA0 is the correct choice instead. HART capability gives you digital communication over the 4-20 mA loop for configuration and diagnostics. The feedback module returns a separate 4-20 mA position signal — useful for DCS or PLC analog inputs without relying on the loop. Rated IP66 per IEC/EN 60529 and NEMA 4X. The mounted pressure gauge block provides local indication of supply and output pressure. If your application doesn't require local gauges, that's additional hardware you're carrying — the sibling 6DR5010-0NG01-0AA0 omits it. The NPT threads suit North American piping standards; for metric threads you would look at variants with 'G' in the connection code, such as 6DR5010-0NG01-0AA0.