A standalone pressure-boosting panel, a small air-handling unit, a sump pump run from a plain Modbus RTU controller — most of these jobs never touch a PLC or a plant network, and the drive for them should not cost as if they did. 6SL3230-3YC10-0UB0 is the minimal G120X build for that territory: the B suffix speaks USS, Modbus RTU and BACnet MS/TP, the 0 suffix leaves out the DC terminals for motors fed over short cable runs, and the result is a 4.2 A (LO), 200–240 V drive in a 73 mm FSA frame with nothing in the order code the panel will never use.

What does the B suffix actually connect to here?

Whichever master the site already has: USS for a legacy Siemens serial link, Modbus RTU for the water controller, BACnet MS/TP where the HVAC head-end expects it — three protocols on the same port, selectable at commissioning from the IOP-2 keypad or the Smart Access WiFi module on a phone. The infrastructure functions stay in the firmware regardless of how simple the network is: PID with sleep and hibernation modes for intermittent demand, pipe filling and dry-run protection for pump duty, fire mode for smoke-control fans, and hardware Safe Torque Off at SIL 3. At 110% / 60 s overload and −20 to +45 °C ambient, the rating curve matches exactly the light infrastructure duty this variant is ordered for.