ATWG

Arbitrary Temperature Waveform Generator

A various waveform shapes creating python script to control a climate chamber via PC.

Releases

Supported climate chambers

• Espec Corp SH-641
  • RS232 communication interface
  • Espec S-2 controller

Install

pip

• Install : python3.7 -m pip install ATWG
• Update : python3.7 -m pip install --upgrade ATWG

Github

git clone https://github.com/akaeba/ATWG.git

Command line interface

Options

Option	Description	Args
—sine	select sine as used waveform
—trapezoid	select trapezoid as used waveform
—minTemp=myVal	sets minimal temperature value
—maxTemp=myVal	sets maximal temperature value
[—invert]	start with lower part of wave
[—period=1h]	period of waveform	dmm:ss, h, m, s
[—startTemp=25]	waves start temperature	start temperature of wave
[—riseTime=0]	positive slew rate, used by ‘—trapezoid’	degree/time, T(min->max); 5C/h, 120min
[—fallTime=0]	negative slew rate, used by ‘—trapezoid’	degree/time, T(max->min); 5C/h, 120min
[—chamber=SIM]	chamber type	SIM, ESPEC_SH641
[—port=]	chamber interfacing port	SH641 default: WinNT: COM1 Linux: /dev/ttyUSB0

Run

Call

[ARGS]: --sine --chamber=SIM --minTemp=10 --maxTemp=60 --startTemp=30 --period=1h

This example starts the waveform generator in the simulation mode. The sine wave has a minimal value of 10°C, a
maximum of 60°C and s start value of 30°C. A full period needs one hour.

Output

Following output is written to the command line interface while the script is active:

Arbitrary Temperature Waveform Generator
  Chamber
    State    : Run /
    Type     : SIM
    Tmeas    : +30.02 °C
    Tset     : +30.06 °C
  Waveform
    Shape    : sine
    Tmin     : +10.00 °C
    Tmax     : +60.00 °C
    Period   : 1h
    Gradient : +2.566 °C/m
Press 'CTRL + C' for exit

Permission denied error on Linux

In Linux has only the root and dialout group proper rights to open
/dev/ttyUSB* devices. Adding the current user to the dialout group
allows ATWG to run without root permissions.

sudo usermod -a -G dialout $USER    # add login user to dialout group
sudo reboot                         # apply settings

Chamber driver

How-to add

The architecture of the ATWG allows the fast integration of a new chamber driver. Therefore is only the import in
the ATWG open procedure necessary. As starting point of a new driver can the class
simChamber serve. There are all ATWG mandatory procedures as simulation
example implemented.

Espec SH641

sh641.py realizes the interface to the climate chamber. Following instruction listing controls the chamber:

from ATWG.driver.espec.sh641 import especShSu     # import driver
myChamber = especShSu()                           # call class constructor
myChamber.open()                                  # open with interface defaults
print(myChamber.get_clima())                      # get current clima
myChamber.start()                                 # start chamber
myChamber.set_clima(clima={'temperature': 25})    # set temperature value
myChamber.stop()                                  # stop chamber
myChamber.close()                                 # close handle

The open procedure accepts as argument a .yml file with the chamber (RS232) configuration. In case of no argument defaults are used.

References

• Espec Corp SH-641
• Fix Serial Permission Error