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LabExT-included APIs

Instrument Drivers

The files in the InstrumentAPI folder implement all the basic necessary instrument-related functionality, mainly communication via the VISA protocol, error checks, setup and teardown. We subclass our instrument drivers to the Instrument class. You can use them as is or override them in the child class of your instrument.

Communication

LabExT uses the VISA protocol to communicate with instruments. We assume that the instruments understand commands written according to the SCPI syntax. The two parts - VISA and SCPI - are independent of each other. If your instrument dates back to the pre-SCPI era or follows some esoteric syntax, then you can still use LabExT but you might need to override all methods defined in Instrument.py that use query, request, command or write and change the command strings. Additionally, you might need to redefine the error_query_string in your child class. Consult your instruments programming manual for the correct command strings.

The instrument class offers the following methods to communicate with your instrument.

write

self.write('SOMETHING') sends the string to the instrument without any additional error or completion checks.

command

self.command('SOMETHING') uses the write method to send the command, waits for the instrument to signal completion and then checks the error queue. If any errors arose during communication then a Exception is raised.

query

self.query('SOMETHING?') sends the string to the instrument and reads the response.

request

self.request('SOMETHING?') sends the string to the instrument, waits for completion, queries the error register and then returns the instruments answer.

The class also offers shortcut functions if you're working with multi-channelled instruments. Instead of the above-mentioned methods use the corresponding _channel version and pass the channel number as well as the command string.
To receive data in raw byte or ASCII format use the members query_raw_bytes and query_ascii_values.

Please see the example on how to implement a new instrument driver and also the the InstrumentAPI code reference for a complete listing of the available methods.

Measurement Algorithms

The files in the MeasAPI folder implement the necessary classes for the LabExT GUI to recognize a measurement and to be able to display the correct GUI elements for parameters and instrument selection.

The default workflow for implementing a new measurement should be:

  1. Create a new file in the measurements folder.
  2. Import all the needed classes.
  3. Create a new subclass of measurement.
  4. Implement the new algorithm by overriding the algorithm member function of the Measurement class.
  5. Track all needed instruments, implement the static get_wanted_instrument member function of the Measurement class.
  6. Track all needed parameters, implement the static get_default_parameter member function of the Measurement class.
  7. Verify that the algorithm is correct.

See the example on how to implement a new measurement and also the MeasAPI code reference.

Info

Measurement code is also usable outside of the LabExT GUI as standalone code.

Export Formats

The files in the Exporter folder implement the necessary classes for the LabExT GUI to recognize a new export format. LabExT can be extended to export measurements into any file format, or even upload measurement data to a remote server.

See the example on how to implement a new export format