Both CIP Safety and FSoE are IEC 61784-3 black-channel safety profiles certifiable to SIL 3 / PL e, and both mitigate the same eight IEC 61784-3 communication error types. The gap is timing architecture: CIP Safety rides EtherNet/IP, which has no hardware time synchronisation, so it uses a software Time Coordination handshake and longer safety cycles; FSoE rides EtherCAT’s Distributed Clocks and runs much faster.
At a glance
| Criterion | CIP Safety (EtherNet/IP) | FSoE (EtherCAT) |
|---|---|---|
| Governing body | ODVA | ETG |
| Standard | IEC 61784-3-2 | IEC 61784-3-12 / ETG.5100 |
| Max integrity | SIL 3 / PL e / Cat 4 | SIL 3 / PL e |
| Typical safety cycle | 10–128 ms | 1–4 ms |
| Typical reaction time | ~20–50 ms | ~2–6 ms |
| Timing mechanism | Time Coordination (T_C), timestamps + time expectation | Watchdog on Distributed-Clock time base |
| Special hardware | None beyond standard Ethernet | EtherCAT Slave Controller (ESC) |
| Ecosystem | Rockwell/Allen-Bradley (GuardLogix) | Beckhoff/ETG, motion, robotics |
Engineering detail
CIP Safety extends the CIP connection model with a safety transport and uses a Time Coordination (T_C) message to establish a shared time base between Safety Originator (controller) and Safety Target (device); the receiver then checks each message against its allowed time window using timestamps and time expectation, without relying on network timing. Unique device identifiers authenticate the connection. Because there is no hardware sync, safety cycles are typically 10 ms or more (10–128 ms) and reaction times ~20–50 ms. CIP Safety needs no special communication hardware, is portable, and is deeply integrated with Rockwell’s GuardLogix / Studio 5000.
FSoE, on EtherCAT’s sub-microsecond synchronised clocks, evaluates its watchdog against a deterministic time base for 1–4 ms cycles and 2–6 ms reaction — the performance leader for high-speed motion and robotics. FSoE adds the least frame overhead (~6 bytes) but requires an ESC per node.
When to choose which
Align the safety protocol with the installed Ethernet infrastructure. CIP Safety for Rockwell/EtherNet-IP plants and discrete manufacturing where ~10–50 ms reaction is acceptable. FSoE for EtherCAT machines needing fast, deterministic safety.
The ISIT-Neperis stacks
ISIT-Neperis’s FSoE stack (IEC 61784-3-12) is pre-certified to SIL 3 and integrates with common EtherCAT masters, giving EtherCAT-based machines the fastest deterministic safety path.