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NTP/PTP Time Synchronization Setup and ENLIGHT Timestamp Formats

Seth M.
Updated

Product: Hyperion si155 / si255 / si255 EV Interrogators
Software: ENLIGHT
Version: 1.0

Overview

The Hyperion interrogator contains an internal clock that timestamps each measurement dataset. For applications that require accurate, absolute time references — such as synchronizing data from multiple instruments or correlating Hyperion data with external acquisition systems — this internal clock can be synchronized to an external time source using NTP (Network Time Protocol) or PTP (IEEE 1588 Precision Time Protocol).

ENLIGHT provides four timestamp format options when saving data, each drawing from either the PC clock or the instrument clock. Selecting the correct timestamp format is essential to ensuring your saved data carries the time accuracy you need.

This article covers:

  • Step-by-step NTP configuration and verification on the Hyperion
  • The four ENLIGHT timestamp formats and when to use each
  • How the instrument clock and PC clock interact
  • A brief overview of PTP (IEEE 1588) as an alternative

Steps

Part 1: Configure NTP Time Synchronization

NTP synchronizes the Hyperion internal clock to an external time server over the network. The instrument must be connected to a network switch with access to the NTP server (via the internet or a local network).

All commands below are entered in the ENLIGHT Command Console, accessible from the Settings tab.

Step 1 — Disable NTP and PTP

Before configuring a new NTP server, disable both time protocols to start from a known state.

#SetNtpEnabled 0
#SetPtpEnabled 0

You can verify the settings with:

#GetNTPEnabled
#GetPtpEnabled

Step 2 — Check the Current Instrument Time

#GetInstrumentUtcDateTime

Step 3 — Set the Instrument Clock to a Known Incorrect Time

Setting the clock to a date far in the past makes it easy to confirm that NTP has successfully updated the time.

#SetInstrumentUtcDateTime 2017 01 01 00 00 00

Step 4 — Verify the Clock Change

#GetInstrumentUtcDateTime

Confirm that the returned value now shows the date you set in Step 3 (January 1, 2017).

Step 5 — Set the NTP Server Address

Provide the IP address of the NTP server. Note: the command requires a numeric IP address, not a domain name.

#SetNtpServer <NTP_SERVER_IP>

Example using a public NIST time server:

#SetNtpServer 129.6.15.28

Replace the IP address above with the address of the NTP server for your network.

Step 6 — Enable NTP

#SetNtpEnabled 1

Step 7 — Verify That the Clock Has Updated

#GetInstrumentUtcDateTime

The returned time should now reflect the current UTC date and time. If the time does not update after a few minutes, verify the following:

  • The Hyperion is connected to a network switch (not directly to a PC).
  • The NTP server IP address is reachable from the instrument subnet.
  • There are no firewall rules blocking NTP traffic.

Part 2: Select the Correct ENLIGHT Timestamp Format

ENLIGHT offers four timestamp formats for saved data. To configure the format:

  1. Open the Save tab in ENLIGHT.
  2. Click the wrench/hammer icon next to the save profile you want to configure.
  3. In the settings window, locate the Timestamp Format field on the far right.
  4. Select the desired format.
Picture1.jpg

Important: Each save profile (Sensors, Peaks, Spectrum, Sensors 2) has its own timestamp format setting. Be sure to update all profiles you are using.

Timestamp Format Options

Format Clock Source Description Best Used When
None N/A No timestamp is saved with the data. Timestamps are not needed, or timing is handled externally.
Full PC clock (initial) + instrument delta ENLIGHT uses the PC clock to create the initial timestamp, then adds an instrument-derived delta for successive timestamps. Local time zone settings are reflected. You need human-readable wall-clock timestamps and the PC clock is sufficiently accurate for your application.
Delta Instrument clock (relative) ENLIGHT records the original UTC time and subtracts successive timestamps to report elapsed time starting at 0.000000. You need relative timing between samples rather than absolute time-of-day.
Native Instrument clock (absolute) ENLIGHT reports the interrogator internal clock reading for each dataset, in microseconds since UTC 00:00:00 on January 1, 1970 (Unix epoch). You are using NTP or PTP synchronization and need the highest timestamp accuracy from the instrument clock. This is the recommended format for synchronized deployments.

Part 3: Understand Instrument Clock vs. PC Clock Behavior

The Hyperion instrument and the host PC each maintain independent clocks. They interact with ENLIGHT in the following ways:

  • Saved data timestamps can use either the PC clock or the instrument clock, depending on the timestamp format selected (see Part 2).
  • ENLIGHT chart timestamps always use the PC clock. The chart time is set when the chart is first turned on or when it is reset. If you need the chart display to show an accurate time, synchronize the PC clock to an external time source (such as a Windows NTP client).
  • Chart time drift: Over long monitoring periods, the chart timestamp may drift relative to the PC clock. The chart time is snapshot at startup and is not continuously re-synchronized. This drift does not affect saved data when using the Native or Delta timestamp formats.

Recommendation: For applications requiring precise absolute timestamps in saved data, use the Native timestamp format with NTP or PTP enabled on the instrument. If the charting display time also needs to be accurate, separately synchronize the host PC clock to an NTP server at the operating system level.

Part 4: PTP (IEEE 1588) — Brief Overview

For applications requiring tighter synchronization than NTP can provide (such as synchronizing multiple Hyperion instruments on the same network), the Hyperion supports PTP IEEE 1588 Precision Time Protocol.

Key facts about PTP on the Hyperion:

  • The Hyperion uses a software-based PTP implementation capable of synchronization on the order of 10 microseconds.
  • PTP requires a grandmaster clock on the same subnet as the instrument. The Hyperion will automatically discover the grandmaster clock.
  • Any standard Ethernet switch will work, though a PTP-compliant switch may yield better results.
  • PTP is supported on firmware version 10.6.11 and above.
  • PTP applies to all x55 product family instruments (si155, si255, si255 EV).

To enable PTP:

#SetNtpEnabled 0
#SetPtpEnabled 1

NTP is enabled by default and must be disabled before PTP can be used. It may take a few minutes after enabling PTP before optimum synchronization with the grandmaster clock is achieved.

When saving data with PTP enabled, use the Native timestamp format to capture the synchronized instrument clock timestamps.

Network topology: Connect the Hyperion interrogator(s), the PTP grandmaster clock, and the data collection PC to the same Ethernet switch on the same subnet.

For detailed configuration, test methodology, and synchronization performance results, refer to Technical Note TN-1355: IEEE 1588 Hyperion Synchronization, available at lunainc.com.

Notes

  • NTP server address format: The #SetNtpServer command accepts only a numeric IP address (e.g., 129.6.15.28), not a hostname or domain name (e.g., time.nist.gov).
  • NTP is enabled by default: New Hyperion instruments ship with NTP enabled. If you are switching to PTP, you must explicitly disable NTP first.
  • Sync signal output: The Hyperion also provides an SMA (SYNC) connector that outputs a square wave sync signal matching the laser scan speed. This can be used to trigger or synchronize external data acquisition equipment independently of NTP/PTP. Refer to the Hyperion User Guide for details on the SYNC output.
  • Closed-loop laser operation: The Hyperion laser operates in a closed loop at a fixed scan frequency. External trigger signals cannot force an acquisition at an arbitrary point in time. Time synchronization via NTP or PTP combined with the Native timestamp allows you to align Hyperion data with other systems in post-processing.
  • Firmware requirement: PTP support requires firmware version 10.6.11 or later. NTP is available on all current firmware versions.
  • Command console access: All commands referenced in this article can be sent from the ENLIGHT Command Console (Settings tab), the LabVIEW simple console example, the Python console example, or any of the Hyperion APIs.

Luna Innovations — Hyperion Platform Documentation

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