PCSDK: Why am I getting a 'no authenticated user' exception?

sammye

Why do I receive the below error when I attempt to update a group signal within another group signal's event?

Exception text: 'The controller has no authenticated user, call Logon( ) to authenticate a user.'

The connection code did not throw any errors when logging on as the default user to a virtual robot and I am able to update the value right after logging in, but I sometimes get an exception within a group signal's event handler when updating another group signal's value. Worked code with a virtual controller:

...
                ControllerInfo controllerInfo = controllers[1];
                if (controllerInfo.Availability == Availability.Available)
                {
                    if (_controller != null)
                    {
                        _controller.Logoff();
                        _controller.Dispose();
                        _controller = null;
                    }
                    _controller = ControllerFactory.CreateFrom(controllerInfo);

                    UserInfo userInfo;
                    if (_controller.IsVirtual)
                        userInfo = UserInfo.DefaultUser;
                    else
                    {
                        userInfo = new UserInfo("abc", "abc123");
                    }
                    _controller.Logon(userInfo);
                }

                Signal signal = _controller.IOSystem.GetSignal("myVariable");
               
                signal.Value= Convert.ToSingle(2);
...

The area where the exception occurs is within an event handler raised when another group signal is set. This makes me wonder if this is a threading issue since the event gets fired on its own worker thread, but I have declared the controller and signal as 'static' so they should be accessible by all threads - please feel free to correct me on anything sounding fishy. Code throwing exception:

        protected override void handleSignalUpdates(object sender, ABB.Robotics.Controllers.IOSystemDomain.SignalChangedEventArgs e)
        {
...
            _groupSignals[mySignal].Value = Convert.ToSingle(Value); // exception here !!!    

Note: The signal causing the event is different from the one being updated within the handler.

sammye

The error I was encountering was cleared up by running the robot controller object in its own thread with a message queue to issue commands. I am still uncertain why making the objects static did not work or if I really got to the root of the problem, but it works for now. I also got to have a lot of fun with semaphores so that was educational.