The Siemens 6DR5211-.....-.... is a SIPART PS2 Smart electropneumatic positioner accepting a 4-20 mA (3/4-wire) input with HART communication, rated for Ex/nEx environments, single-acting, in a small aluminum enclosure for pneumatic linear and part-turn actuators.
This part carries an NRND (Not Recommended for New Designs) status, meaning Siemens no longer targets it for new projects. It remains available through the supply chain for existing BOM lines, but procurement should plan for a transition. The product class is C: manufactured/produced to order, which means it is not stocked as a standard off-the-shelf item and cannot be returned for credit. Sourcing is handled via RFQ — quoted to order against your specific requirement.
RoHS compliant since 31-12-16. REACH Article 33 information is available on the current candidate list.