metrohm_autolab_python

This exemplifies how to run a Metrohm Autolab PGSTAT302N with FRA/EIS and the true linear CV option in Python using the SDK. Use it at your own risk as this comes without any promise of use or safety.

Installing all the prerequisites

Go install the SDK and make sure to install both the Nova 1.11 and Nova 2.x version. You will then need to install pythonnet of the latest version do this by ''' pip install pythonnet ''' This will give you the possibility of laoding a dll and interface it relatively esay from python 3.7+.

Make you own procedures

After having installed the SDK and Nova 1.11 and 2.x you can go ahead and program your own procedures. Any procedure is comprised of commands that have CommandParameters i.e. you make a procedure with the command of applying a potential which then has the command parameter "applycurrent" (you specify that name) with a "Setpoint value" that you set to say 1e-5A. What this code does is essentially nothing but loading a predefined procedure and allowing you to redefine the setpoint values. This results in having general procedures like having one general Chronoamperometry prodeure where you then change values like duration or stop criteria. The herein shown examples are nothing but templates as procedures can be arbitraily complex.

How does it work?

This code simply loads a predefined procedure:

self.proc = self.inst.LoadProcedure(self.proceduresd[name])

as you might want to change some values from emasurement to measurement you need to go to the respetive commands and command parameters

for comm, params in setpoints.items():
    for param, value in params.items():
        self.proc.Commands[comm].CommandParameters[param].Value = value

Sometimes the command parameters in a procedure are named by their default values (e.g. CVLinearScanAdc164) so that you need to find out what the Command names are do this by calling:

list(myProcedure.Commands.IdNames)

of if you want to know what you can set as setpoint call:

list(myProcedure.Commands['myCommandName'].CommandParameters.IdNames)

You can design a procedure in Nova 2.x but sometimes they are not compatible with the SDK. I experienced this with anything regarding the FRA/EIS module. The most simple fix is to just write the procedure in Nova 1.11 if you ecounter any compatility issues. If you want you can have relatively low access to the data like the actual readout of the X and Y channel of your FRA shall you ever need it. I added some live data output but typically just display the live data on an oscilloscope. Fell free to add that capability.

Starting a measurement

With this code it is possibile to start an electrochemical measurement with nothing but a .json string or python dict. Starting a CV scan can be done like this:

autolab_conf = dict(basep = r"C:\Program Files\Metrohm Autolab\Autolab SDK 1.11",
                    procp = r"\conf\echemprocedures",
                    hwsetupf = r"C:\ProgramData\Metrohm Autolab\12.0\HardwareSetup.AUTXXXXX.xml",
                    micsetupf = r"C:\Program Files\Metrohm Autolab\Autolab SDK 1.11\Hardware Setup Files\Adk.bin",
                    proceuduresd = {'cp': r'CP.nox',
                                    'ca': r'CA.nox',
                                    'cv': r'CV.nox',
                                    'eis': r'EIS.nox',
                                    'ocp': r'OCP.nox'})
conf_cv = {'procedure': 'cv',
           'setpoints': {
               'FHSetSetpointPotential': {'Setpoint value':0},
               'FHWait': {'Time':2},
               'CVLinearScanAdc164': {'StartValue': 0.0, #V
                                      'UpperVertex': 0.5, #V
                                      'LowerVertex': -0.5, #V
                                      'NumberOfStopCrossings': 2,
                                      'ScanRate': 0.1}}, #V/s
           'plot': 'tCV',
           'onoffafter': 'off',
           'safepath': r'C:\Users\Helge\OneDrive\Documents\Engineering\autolab\data',
           'filename': 'cv.nox',
           'parseinstructions': ['CVLinearScanAdc164']}
                                    
a = Autolab(autolab_conf)
a.performMeasurement(conf_cv)
a.disconnect()

This will configure the potentiostat and perform a CV measurement with a pre Potential which is held for 2 seconds. The program with save the data in the native .nox format and export the measured data as a .json file