allows reordering of data without changing master code. 9. Diagnostic Features | Feature | Description | | :--- | :--- | | Working counters (WKC) | Each datagram includes a 16-bit counter; each node increments it if operation succeeds – instant mismatch detection | | Link status per port | Each slave’s PHY reports up/down | | Loopback detection | Master can detect ring opens | | Register diagnostics | Each slave exposes error counters, temperature, voltage (if implemented) | | Distributed Clock drift | Monitored automatically |
| Address Type | Purpose | | :--- | :--- | | | Physical order in the ring (auto-configured) | | Node addressing | Fixed station alias (set in EEPROM) | | Logical addressing | FMMU (Fieldbus Memory Management Unit) maps physical I/O into a 4 GB virtual address space – allows master to read/write scattered I/O with one datagram | ethercat
No need for managed switches, reducing cost and complexity. 3. Performance Metrics (Measured) | Metric | Typical Value | | :--- | :--- | | Cycle time | 31.25 µs (minimum theoretical), 50–250 µs typical | | Jitter | < 1 µs (deterministic, not statistical) | | Number of slaves | Up to 65,535 | | Process data per frame | Up to 1498 bytes (standard MTU) or 1498* (jumbo frames) | | Sync accuracy | < 1 µs between slaves (Distributed Clocks) | allows reordering of data without changing master code
This makes it the dominant choice for where deterministic latency matters more than raw bandwidth. Its weakness is the requirement for specialized slave hardware and a real-time capable master – but in return, it scales from a handful of I/O points to thousands with consistent, predictable timing. 1 µs (deterministic