Why choose PROFIsafe over standard F-DI for STO in distributed conveyor drives?

PROFIsafe transmits the STO safety signal over the same PROFINET cable that carries speed setpoints, diagnostic data, and drive parameters — no additional wiring required. In a conveyor system with ten distributed G115D drives, the standard F-DI approach requires a dedicated fail-safe digital input pair to each drive: twenty conductors running from the safety relay or safety PLC across the conveyor length. With PROFIsafe, each drive's STO function is addressed as a logical safety device on the PROFINET network, and the safety telegram rides on the existing Ethernet cable. The engineering difference is an order-of-magnitude reduction in safety wiring when the drive count exceeds a handful. For conveyor OEMs and system integrators, this reduces cabinet space (fewer safety relay outputs), installation labor (one cable per drive instead of three), and commissioning time (safety addressing in TIA Portal instead of point-to-point continuity checks).

How does the integrated C2 line filter simplify EMC compliance in multi-drive installations?

Each AF0 drive includes a factory-installed C2 line filter that limits conducted emissions to Category C2 levels per EN 61800-3. In a daisy-chained power distribution topology — where a single 400 V feeder supplies multiple G115D drives along a conveyor line — each AF0 node is independently C2-compliant at its supply terminals. The system integrator does not need to model cumulative conducted emissions across the daisy chain or derate filter performance based on the number of drives sharing a feeder. This per-drive EMC approach is particularly valuable when drives of different power ratings (1.5 kW, 2.2 kW, 3 kW) share the same feeder, because filter sizing is handled at the individual drive level rather than requiring a single external filter rated for the total feeder current.

What safety architecture options does PROFIsafe enable in conveyor networks?

PROFIsafe allows per-zone safety control without per-zone wiring. A single safety PLC (S7-1200F or S7-1500F) can selectively trigger STO on individual G115D AF0 drives based on zone occupancy, light curtain status, or emergency-stop button location. For example, an accumulation conveyor with five zones can stop only the zone where an operator has entered, while upstream and downstream zones continue running. With F-DI-based STO, achieving this level of zone granularity would require a dedicated safety relay output per zone and individual F-DI wiring to each drive — five times the safety I/O hardware. The AF0 variant also supports the optional SLS (Safely Limited Speed) license, which adds a second safety function over the same PROFIsafe channel without additional hardware.

Frequently Asked Questions

Is a separate PROFIsafe address required for each drive?

Yes. Each G115D AF0 drive occupies one F-address on the PROFINET safety network. The F-address is assigned during commissioning in TIA Portal using the SINAMICS Startdrive plug-in. The PROFIsafe watchdog time is configurable per drive, typically set between 100 ms and 500 ms depending on the application's safety response time requirement.

Does PROFIsafe add latency to the STO response compared to F-DI?

The PROFIsafe protocol adds a deterministic processing delay of approximately 10-30 ms depending on the F-monitoring cycle time. For conveyor applications, this is well within the typical safety response budget. If sub-10 ms STO response is required — rare in conveyor systems — the F-DI input on the same drive can still be used as a parallel safety path.