My experiment setup with PyLECO

[BenediktBurger]

As an example, how PyLECO can be used in an experimental environment, I describe my setup.
Maybe it gives some inspirations.

Infrastructure

Hardware

We're two projects in the lab, each with its own measurement computer (Windows).
These computers are connected to measurement devices and are the main terminal for researchers controlling the devices and collecting data.
We share some resources (Lasers) which are connected to a third computer.
All computers are connected via LAN.

Software

Each one of these three computers run a Coordinator, a proxy_server, and a Starter.
We installed these three programs as windows services with the NSSM (non sucking service manager) in order to start them at computer startup without user interaction.

The Coordinators connect to each other in order to establish a LECO network.

Measurement Setup

For a measurement, we need to control devices (communicate with them and user interface) and to collect data.

Device Communication

For each device, there is a Starter script in a folder (see in this repo).
Some scripts just regularly read some value and publish them via the data protocol (without connection to the control protocol), other scripts use the Actor in order to be controllable.

User Interface

The user interface is heavily based on the pyleco-extras repository.

Introduction

The BaseMainWindow offers a Qt Main Window with a Listener (from pyleco), such that the program can send and read LECO messages and such that it can be controlled via LECO messages.

With the StarterGUI we communicate with the Starter in order to see, which tasks are started and to start or stop them as required.

Main Control Interface

The main control interface uses several directors (all using the communicator of the main window) to control the instruments:

• In a first step, it starts tasks, such that the instruments are available via LECO,
• it regularly polls some values from devices,
• after user interaction, it sends commands to the instruments' Actors.

As device interaction can take some time, this main control interface does use the asynchroneous capabilities of the Director: You can send a message via the async methods, which returns th conversation_id. Later you can read the response, whenever you which, or you can associate the response to the calling method after arrival.

This main control window can also control the shared laser systems connected to the shared computer as if they were local.

Specialized Interfaces

The main control window does not have all the options for all the devices, lest the interface is cluttered.
We have some more specialized programs, for example a GUI controlling stepper motors, which offers finer control over the motors than the main control window.
Thanks to LECO, both programs can control and read the same stepper motor, because the communication is routed through the same Actor.

Other software elements control special measurement software and publish their data via the data protocol.

Maintenance

Recently I had to add another measurement device (on another computer) to the main control window which was quite simple:

1. Add another script to the scripts on the shared computer (just an Actor running the device's driver),
2. Add GUI elements to the control window,
3. Use a Director to read that device.

Regularly, I control some parts of the experiment from my office, as the control window can be run anywhere in the network, due to LECO communication.

Data Acquisition

We acquire our data with the DataLoggerGUI from pyleco extras, which is a GUI containing a DataLogger from PyLECO internally.
This DataLogger listens to data published via the data protocol and creates data points from it.

The GUI interface allows to see graphs of the collected data in real time (pyqtgraph) with dockable graphs.

The DataLoggerViewer uses the same interface to show the data of a file saved by the DataLogger.

Measurement Workflow

Workflow for a typical measurement.

Preparation

1. The infrastructure (Coordinator, Starter, proxy_server) is installed as windows services and therefore is already started at computer startup.
2. A script tells the the Starter which tasks to start. That ensures, that communication with all needed devices (via their Actors) is possible.
3. I start the GUIs needed: The Lasercommander controlling the laser system and a DataLoggerGUI from pyleco-extras for logging data.
4. The Lasercommander starts the Laser system and allows to control all the parameters of the laser system, showing several relevant parameters.
5. The LogLogger from pyleco-extras collects log entries from the different programs.

Measurement

For a measurement, I use the Lasercommander or other specialized GUIs (for example one controlling stepper motors) to change parameters, while the DataLoggerGUI collects data.

Evaluation

The DataLoggerViewer (also from pyleco-extras) plots the data collected by the DataLogger.
Specialized scripts allow custom evaluation (fitting functions to the data etc.).

Thanks

Thanks for reading.

If you have questions, don't hesitate to ask!