IRIG-B Protocol Description
IRIG-B is one of a family of precision time protocols originally defined by the Inter-Range Instrumentation Group (IRIG) of the US army. Historically, IRIG-B has been widely used by electric utilities, industrials, and others to ensure precise time synchronization of power system devices, such as breakers, relays and meters.
IRIG-B is typically distributed as a DC level shift (DCLS), pulse-width coded signal ("unmodulated IRIG-B") or as an amplitude-modulated signal based on a sine wave carrier with a frequency of 1kHz ("modulated IRIG-B"). The most common version of IRIG-B is unmodulated (5V DCLS) with full date/time, including the year, transmitted once per second.
For more details on IRIG-B protocol and its applications, see Tech Note: Overview of IRIG-B Time Code Standard (TN-102)
Time Sync: PM8000 Power Meters
Modern industrial/commercial power systems require precise time synchronization of all devices to ensure meaningful data for analysis and reliable operation. PM8000 meters from Schneider Electric support IRIG-B (and also ASCII/RS-485) protocol for precision time sync. CyTime™ SER-3200/2408 Sequence of Events Recorders from Cyber Sciences can generate IRIG-B to synchronize these power meters, greatly simplifying time sync design. SER-3200/2408 Event Recorders accept a variety of time source options and then sync with each other using PTP. In turn, a PTP slave can also output a legacy protocol (e.g., IRIG-B) to devices that do not support PTP (e.g., PM8000).
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PM8000 Time Sync Wiring
A PM8000 can decode an IRIG-B time sync signal via a dedicated digital input. To take advantage of PTP (IEEE 1588) precision time sync over Ethernet, an SER-3200-PTP (or SER-2408-PTP) is configured as a time sync master with IRIG-B as its output (via PLX-5V).
When using IRIG-B for time synchronization, PM8000 meters are configured for time sync via a dedicated digital input. IRIG-B can only be connected to one of the digital inputs located on the meter base, not an option module. The device must be set as follows:
- Clock Source = COMM
- Time Sync Source = IRIG-B
- Input Mode = IRIG-B (for the digital input wired to the IRIG-B signal)
► For more details, see Tech Note: Overview of IRIG-B Time Code Standard (TN-102)