How to start TwinCAT with Pyads

I'm trying to control my Beckhoff device by means of Python Pyads wrapper.

If TwinCAT is in Config mode on my target device, is it possible to start it with a Python command?

I don't think this is possible from pyads. It is possible to do it with the TwinCAT automation interface. See example code from InfoSys:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using EnvDTE100;
using System.IO;
using TCatSysManagerLib;

namespace ActivatePreviousConfiguration
{
    class Program
    {
        static void Main(string[] args)
        {
            Type t = System.Type.GetTypeFromProgID("VisualStudio.DTE.10.0");
            EnvDTE.DTE dte = (EnvDTE.DTE)System.Activator.CreateInstance(t);
            dte.SuppressUI = false;
            dte.MainWindow.Visible = true;

            EnvDTE.Solution sol = dte.Solution;
            sol.Open(@"C:\Temp\SolutionFolder\MySolution1\MySolution1.sln");

            EnvDTE.Project pro = sol.Projects.Item(1);

            ITcSysManager sysMan = pro.Object;

            sysMan.ActivateConfiguration();
            sysMan.StartRestartTwinCAT();
        }
    }
} 

Then you could use PythonNET to call this program from Python.