2 inputs determine the right valve terminals & regulator.

A distributor-facing pre-quote checklist. If the customer answers most of these at the first call, the second call is the quote.

1. 01
   Is the plant doing — or planning — predictive maintenance, MES integration, or smart-factory diagnostics?

   The IO-Link pivot question. Yes = IO-Link terminal, full diagnostic package, fieldbus gateway matched to the PLC's network protocol (EtherNet/IP for Allen-Bradley / Rockwell; PROFINET for Siemens; EtherCAT for motion-heavy machines). No, but they want to reduce wire count = IO-Link sold on wiring savings, diagnostics as latent value. Neither = standard sub-base manifold with the IO-Link upgrade path mentioned as future option.
2. 02
   What's the fieldbus protocol on the PLC network?

   Only matters if the answer to the IO-Link question is yes — but then it matters absolutely. The gateway is firmware-locked to one protocol (EtherNet/IP, PROFINET, EtherCAT, DeviceNet, Modbus TCP). A PROFINET unit cannot be reconfigured to EtherNet/IP in the field. Get the protocol confirmation in writing from the customer's controls engineer — do not infer from the PLC brand alone (Rockwell plants sometimes have legacy PROFINET lines).