IRIG‑B Synchronization (Arbiter protocol) — Interbyte Time Adjustment on SAGE RTU

Issue:
IRIG‑B time synchronization from an Arbiter source is intermittent or fails; the SAGE Arbiter task reports receive errors and time events are not being applied reliably.

Product:
SAGE RTU (Arbiter IRIG‑B protocol)

Environment:

SAGE RTU GUI using Arbiter IRIG‑B for time sync

Cause:
The Interbyte Timer in the Arbiter protocol configuration is expiring before the second byte of each transmission arrives. In a captured session, the 2nd byte was received ~100 ms after the 1st byte (Protolyzer highlighted in purple as a timing violation), while the SAGE Interbyte Time was set to the default 50 ms. When this timer expires, the Arbiter task interprets it as a reception error and may discard the message, disrupting synchronization.

Resolution:

1. Increase the Interbyte Time in the SAGE Arbiter protocol configuration from the default 50 ms to 150 ms.
2. Apply/Save the protocol changes and restart the Arbiter task (or the RTU communication service, if required by your configuration).
3. Retest with a Data Trap on the same port and review in Protolyzer:
   • Confirm that the 2nd byte timing no longer violates the Interbyte parameter (no purple timing flags).
   • Verify that the Arbiter task logs no further receive‑timeout or frame errors.
4. Monitor synchronization: check that time events are now accepted and that the RTU clock remains aligned.
5. If needed, fine‑tune the Interbyte Time upward in small increments to accommodate line latency or source behavior; avoid setting it excessively high to prevent unintended message grouping.

Notes / Tips:

• If issues persist, also review baud rate, parity, and stop bits on both Arbiter and SAGE ends, cable integrity, and grounding/noise conditions.
• Keep a short capture pre‑ and post‑change to document improvement for your records.

Publicerad för: Schneider Electric Sverige