This is the oven control program used in the ErYbLi experiment of the Quantum Optics Group at Kyoto University.
It is intended to run on a Raspberry Pi with the corresponding Raspberry Pi
touchscreen installed. Additional technical details on the hardware
implementation can be found in the README.txt file.
ErYbLi-oven_control is built using Python (version 2.7) and wxWidgets (version 3.0).
Normal interaction with the program is through a full-screen graphical user interface. This interface is divided into five sections that are represented as separate notebook tabs and that can be displayed as necessary. We will take a look at the different tabs now.
In the Oven selection area the available ovens are listed as buttons. Selected ovens are displayed in green and it is those ovens that will be brought to their operating (that is high) temperatures. The operation mode of the program is selected in the Action selection area. Here, the various temperatures ramps for the selected ovens can be selected. Currently active ramps are in yellow, once the target temperatures have been reached the button turns green. Finally, the Oven status area displays the status of the interlock system and, if applicable, the remaining time for the current ramp to finish. The interlock system monitors the status of the cooling water flow, the temperatures of all thermocouples, the resistances of all heating elements, the status of all power supplies, and the information coming from one or more UPS systems. Good interlocks are green, disabled interlocks are gray and failed interlocks are red. A failed interlock triggers an emergency ramp of all ovens to OFF.
This page informs in the Oven temperatures area graphically and numerically on the current actual oven temperatures and their set values. The Power supplies area provides similar information on all power supplies. Clicking on the temperature graph toggles between a plot of the temperatures and a plot of the temperature errors. Correspondingly, clicking the power supply graph switches between power and current information. Unneeded information can be removed from the plots by clicking on the corresponding row of the left side table.
This tab allows for each heater to quickly modify the low and high temperature setpoints, the parameters of the PID control loop and the ramping speeds. Additional information on the associated power supplies and the maximum allowable temperature is also shown. As that information, however, is very relevant to the secure operation of the oven system it cannot be modified through the graphical user interface. Instead, the configuration file needs to be adjusted manually.
This page exposes some of the most fundamental settings of the program, such as the mail recipients for status messages and some options on the monitor plots and the database logging facility. For a complete control of the program settings, however, it is necessary to manually edit the configuration file.
To help with operating the oven at inconvenient times, the program includes the possibility a execute the actions from the main control page also via a timer mechanism. This allows, e.g. to start warming up the oven at a very early time in the morning and to have everything up and running by the time the crew arrives in the laboratory.
As mentioned before, ErYbLi-oven_control has been developed for and is in use at the ErYbLi experiment of the Quantum Optics Group at Kyoto University. Below some pictures of the actual are show to give a better idea of what we are talking of here in the first place.
First, a general overview of the setup. On an optical table the three-species oven system is installed as part of the main vacuum system. It is visible as the shiny stainless-steel tube in the background. A supporting ion pump is visible on the right corner of the table. A flow sensor (central in the picture) monitors the flow rate in the water cooling system. The control software is installed on a Raspberry Pi, version 3, that is mounted in a case together with the Raspberry touchscreen. The case is fixed to the table by a custom, 3d-printed adapter pedestal.
The necessary electronics is mostly within a secondary box just behind the Raspberry Pi. It contains the MAX31855 thermocouple readout boards, an isolated RS232 serial port for communication with the power supplies, the connection to the water flow sensor and a piezo buzzer. The electronics box connects to the Raspberry Pi GPIO connector via a flatband cable.
Below the optical table is space to house the power supplies for the heating elements. They are manufactured by Takasago, the smaller ones are from the older KX series and provide between 100 and 210 W, the larger ones are more recent ZX series supplies and provide up to 400 W. (Note that ZX power supplies need to be put into EX compatibility mode. This is done by adjusting function setting 61 to 1.) The first power supply is connected to the RS232 serial port of the electronics box and the other supplies are daisy-chained to form a data bus where each power supply has its individual address.
For any comments and/or bug reports please report to the author, schaefer@scphys.kyoto-u.ac.jp.