A small 0.75 kW axis only needs to start, stop, and trip safe when the guard opens — it does not need to be a network citizen. The 6SL3520-2XE00-7AB0 is a wall-mounted IP66 drive fed from 480 V that runs on local I/O with STO wired straight to its safety terminals, so there is no fieldbus node to commission, license, or fault-hunt.

When does dropping the fieldbus actually pay off?

It pays off wherever adding a PROFINET or AS-Interface node costs more than the function it adds — a standalone conveyor zone, a local agitator, a machine-mounted auxiliary the PLC already handles with hardwired I/O. You give up remote diagnostics and parameter access from the engineering station, so if you need to tune or monitor it from the network, the 7AF0 (PROFINET) or 1AA0 (AS-Interface) siblings fit better. Choose local I/O only when the axis is genuinely self-contained.