Free tool · PROFINET
PROFINET cycle time calculator
Real PROFINET cycle time is bounded by max(update_time, n_devices × frame_time × 2). This tool estimates the theoretical cycle by profile (RT class 1 vs IRT class 3) and tells you whether you have the bandwidth headroom or whether you need to increase the update time / split devices across IO controllers.
Free · no sign-upLast updated: 2026-05-20
On the same IO controller (max 200)
bytes
1 to 1440 bytes
✅ Bandwidth headroom sufficient
- Profile
- PROFINET RT (Real-Time class 1)
- Bus load per cycle
- 448 µs
- Theoretical min cycle
- 0.45 ms
- Actual cycle time
- 8.00 ms
- % bandwidth used
- 5.6 %
- Headroom margin
- 94.4 %
Assumptions: RT frame ~80-120 bytes on the wire, 100 Mbps full duplex, linear payload adjustment above 40 bytes.
How to use
1. Pick the profile: RT for most projects, IRT for motion / robotics.
2. Enter the IO device count on the same IO controller.
3. Pick the target update time (1-512 ms).
4. Enter the average payload per device (64 bytes default).
5. Keep the headroom margin > 30% (otherwise raise update time or split devices across two controllers).