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IEC 62413: Real-time Ethernet EtherNet/IP with Time Synchronization – CIP Sync for Precision Industrial Timing
IEC PAS 62413 | First Edition 2005 | CP 2/2 with PTP
1. Introduction to CIP Sync
IEC PAS 62413 adds precise time synchronisation to EtherNet/IP (CP 2/2) by integrating IEEE 1588/IEC 61588 Precision Time Protocol into the object model. This enables deterministic time-aware communication for demanding automation applications.
CIP Sync enables sub-microsecond synchronisation accuracy across EtherNet/IP networks for multi-axis motion control below 1 ms cycle times.
2. Time Sync Object Model
2.1 Object Class
| Attr ID | Name | Type | Description |
|---|---|---|---|
| 1 | CurrentTime | STIME | Local time value |
| 2 | PTPTime | STRUCT | IEC 61588 PTP format |
STIME is an 8-octet fixed-length type expressing time in nanoseconds.
2.2 Management_Message Service
The Time Sync Object provides the Management_Message service for PTP clock commands including ObtainIdentity, InitializeClock, SetSubdomain, and SetTime.
Implementers must follow parameter encoding carefully, including AREP and path information.
3. Management Commands
| Command | Description |
|---|---|
| ObtainIdentity | Retrieves PTP clock identity |
| InitializeClock | Initialises local PTP clock |
| SetSubdomain | Configures PTP subdomain |
| SetSyncInterval | Sets sync message interval |
| SetTime | Sets local clock time |
| Enable/DisablePort | Controls PTP port state |
4. Engineering Design Insights
CIP Sync requires careful PTP clock hierarchy planning. A grandmaster clock serves as primary reference. Boundary clocks distribute time across network segments. Transparent clock switches compensate for switch-induced delay. CurrentTime provides simple nanosecond timestamps; PTPTime preserves full IEC 61588 structure for interoperability.
Use boundary clocks at network segmentation points to prevent jitter accumulation across router boundaries.
5. Frequently Asked Questions
Q: What accuracy can CIP Sync achieve?
A: Sub-microsecond with hardware timestamping; 10-100 µs software-only.
A: Sub-microsecond with hardware timestamping; 10-100 µs software-only.
Q: Does it need specialised switches?
A: Basic sync works with standard switches; accuracy improves with IEEE 1588 transparent clock switches.
A: Basic sync works with standard switches; accuracy improves with IEEE 1588 transparent clock switches.
Q: How does it relate to IEEE 1588?
A: CIP Sync implements PTP per IEC 61588; the Time Sync Object provides an IEC 61158 Type 2 interface.
A: CIP Sync implements PTP per IEC 61588; the Time Sync Object provides an IEC 61158 Type 2 interface.
Q: Can it coexist with standard I/O traffic?
A: Yes, using UDP ports 319 (event) and 320 (general).
A: Yes, using UDP ports 319 (event) and 320 (general).
