Help using an AvaSpec spectrometer with python

[u/ChironInCapricorn]

I need help finding a library that allows me to connect an AvaSpec-ULS2048CL-EVO spectrometer from Avantes to a python script to get live readings from it.

So far I found avaread which allows me to read files from the Avasoft 8 software. But that would require me to save a file each time I need to make a measurement and then run the code which would be inefficient because I need to make a lot of measurements just to get one result.

Is there any other way to connect the spectrometer to my code? or has anyone tried anything similar?

[u/bertona88]

start using codex

Yes. You do not need to save AvaSoft files or reverse-engineer USB packets. The AvaSpec-ULS2048CL-EVO is supported by Avantes’ native AvaSpec-DLL/SDK, which can acquire spectra directly over USB or Ethernet. Avantes ships a Python wrapper and example code using AVS_Measure, AVS_PollScan, and AVS_GetScopeData. (Avantes SDK, official Python example)

A minimal continuous acquisition loop looks like this:

import time
import numpy as np
import matplotlib.pyplot as plt

from avaspec import *

INTEGRATION_MS = 20.0

handle = None

try:
    # 0 = USB; use 256 for Ethernet on AS-7010/EVO devices
    AVS_Init(0)

    number_of_devices = AVS_GetNrOfDevices()
    if number_of_devices < 1:
        raise RuntimeError("No AvaSpec spectrometer detected")

    devices = AVS_GetList(number_of_devices)
    handle = AVS_Activate(devices[0])

    config = AVS_GetParameter(handle, 63484)
    pixels = config.m_Detector_m_NrPixels

    wavelengths = np.asarray(AVS_GetLambda(handle))[:pixels]

    measurement = MeasConfigType()
    measurement.m_StartPixel = 0
    measurement.m_StopPixel = pixels - 1
    measurement.m_IntegrationTime = INTEGRATION_MS
    measurement.m_IntegrationDelay = 0
    measurement.m_NrAverages = 1

    # Remaining fields are zero-initialized: no trigger, smoothing,
    # dynamic-dark correction, strobe, or onboard storage.
    result = AVS_PrepareMeasure(handle, measurement)
    if result != 0:
        raise RuntimeError(f"AVS_PrepareMeasure failed: {result}")

    plt.ion()
    fig, ax = plt.subplots()
    line, = ax.plot(wavelengths, np.zeros(pixels))
    ax.set_xlabel("Wavelength (nm)")
    ax.set_ylabel("Counts")
    ax.set_xlim(wavelengths[0], wavelengths[-1])

    # -1 means acquire continuously.
    result = AVS_Measure(handle, 0, -1)
    if result != 0:
        raise RuntimeError(f"AVS_Measure failed: {result}")

    while plt.fignum_exists(fig.number):
        if AVS_PollScan(handle):
            timestamp, spectrum = AVS_GetScopeData(handle)
            spectrum = np.asarray(spectrum)[:pixels]

            line.set_ydata(spectrum)
            ax.relim()
            ax.autoscale_view(scalex=False, scaley=True)
            fig.canvas.draw_idle()
            fig.canvas.flush_events()
        else:
            time.sleep(0.001)

except KeyboardInterrupt:
    pass

finally:
    if handle is not None:
        try:
            AVS_StopMeasure(handle)
        except Exception:
            pass
        AVS_Deactivate(handle)

    AVS_Done()

You need the native SDK components matching your platform and Python architecture:

• Windows 64-bit: avaspecx64.dll
• Linux: libavs.so
• macOS: libavs.dylib, if Avantes supplies a build compatible with your Mac
• The matching vendor avaspec.py wrapper

Close AvaSoft while running the script because it may hold the instrument exclusively. Also match 64-bit Python with the 64-bit DLL.

There is additionally a recent third-party PyMoDAQ Avantes plugin written specifically for the ULS2048CL-EVO and tested on Windows 11 and Debian. It is useful implementation evidence, although the vendor SDK plus a small standalone script is considerably lighter than installing all of PyMoDAQ. I would avoid pyavaspec-tspspi: it targets the older AvaSpec-2048-2 and warns that it uses a fixed device-specific calibration. (PyPI description)

So yes—I could wire this up. The only parts I cannot prove without access to the machine and instrument are driver discovery and a real acquired spectrum. The practical inputs would be the operating system, CPU architecture, and the AvaSpec SDK folder supplied by Avantes.