This is a python package that serves as a driver for STXL cameras connected via ethernet. All communication with the camera is via HTTP requests to the camera's built-in web server.
To install, use:
pip install stxldriver
This package requires python >= 3.5 as well as the numpy and requests packages.
This package has only been tested on STXL-6303 cameras, but should work for other STX/STXL cameras with the same built-in web server.
All communication with a camera requires that you first create a driver object, e.g.
from stxldriver.camera import Camera
C = Camera(URL='http://10.0.0.3')
Most of the low-level functionality available through the web server can be access using Camera methods,
but you can normally just use this higher-level API:
C.initialize(reboot=True, binning=2, temperature_setpoint=15)
C.take_exposure(exptime=0, fname='zero.fits', shutter_open=False)
C.take_exposure(exptime=10, fname='dark.fits', shutter_open=False)
C.take_exposure(exptime=100, fname='science.fits', shutter_open=True)
If you have a filter wheel installed, you can also control it through the same object, e.g.
C.set_filter(filter_number=3)
All output is sent to the standard python logging facility, so you can easily control how much you want to see and where it goes.
See the comments in stxldriver/camera.py for more detailed documentation. The scripts described below also provide useful
examples of using this driver.
This package includes two command-line scripts: stxlcalib and stxlstress. The first is to automatically collect a sequence of calibration zeros, darks and flats. The second starts a long-running "stress test" of your camera and this driver, performing a repeated cycle of open-shutter exposures. Use this to checkout a camera or observe the temperature latchup recovery described below.
All STXL-6303 cameras I have used periodically experience "temperature latchup", where the temperature is significantly higher than the setpoint and the cooling power is at 100%. The take_exposure method demonstrated above can automatically detect and recover from this condition, without requiring a power cycle. The recommended pattern for this is:
C = Camera(...)
init = lambda: C.initialize(...)
init()
success = C.take_exposure(..., latchup_action=init)
This approach will automatically detect a latchup, and reboot and reconfigure the camera when one occurs, then return False.
Writing a new value of the fan setpoint is not reliable, and will sometimes appear to succeed but actually not change the previous value. For this reason, the initialize method will not complain when this happens, but you will see an INFO logging message like:
09/20/2019 17:13:49 INFO wrote FanSetpoint=100.0 but read 63.0.
09/20/2019 17:13:49 INFO wrote Fan=2 but read 1.
Note that this is only an issue if you are trying to set a manual fan speed, and setting the more critical temperature setpoint apopears to be reliable.
To handle this in your own code, if you are working at a lower level than initialize and take_exposure, you will need to catch the RuntimeError that is raised whenever any configuration data is not correctly updated, e.g.
try:
self.write_setup(Fan=2, FanSetpoint=100.0)
catch RuntimeError:
pass
This driver has some potentially useful INFO and DEBUG messages but, if you set the global log level to these values,
you will be swamped by log messages from the lower-level networking packages. To avoid this, set their log levels individually, e.g.
import logging
logging.basicConfig(level=logging.DEBUG, ...)
logging.getLogger('urllib3').setLevel(logging.INFO)
logging.getLogger('requests').setLevel(logging.WARNING)