Unknown system error (VISA error code 1073807360) From .NET Library

[runverzagt]

Hello,

I am running into a  very difficult issue using the VisaNS library in C# .NET. I have created a class called FactoryInterface with the following constructor:

public class FactoryInterface : ICommonControl
    {
        protected MessageBasedSession _mbSession;

        public FactoryInterface(string com_port)
        {
            SerialSession ss;

            _mbSession = new SerialSession("COM14");
            ss = (SerialSession)_mbSession;

            ss.BaudRate = 57600;
            ss.DataBits = 8;
            ss.StopBits = StopBitType.One;
            ss.Parity = Parity.None;
            ss.Timeout = 1000;
            ss.TerminationCharacter = 0x0d;
        }
}

I then create an object of Factory interface and call the following function, SendCommand with the parameters "get netconfig\r" and false:

public void SendCommand(string cmd, bool getError)
{
    _mbSession.Write(cmd + "\r");
}

Which returns the following exception:

Unknown system error (miscellaneous error).  VISA error code -1073807360 (0xBFFF0000), ErrorSystemError

In order to test the device I open VISA Test Panel. I configure the device with the same parameters as above and send the same string. The write completes without error.

When I capture both communications using NI I/O Trace, I see the following descriptions for the successful and unsuccessful communications, respectively:

2.  viWrite (ASRL14::INSTR (0x00C7DA10), "get netconfig.", 14 (0xE), 14 (0xE))
Process ID: 0x00005530         Thread ID: 0x000052C0
Start Time: 10:11:58.1070      Call Duration 00:00:00.0002
Status: 0 (VI_SUCCESS)

> 27.  viWrite (ASRL14::INSTR (0x00000001), "get netconfig.", 14 (0xE), 0 (0x0))
> Process ID: 0x00005404         Thread ID: 0x0000569C
> Start Time: 10:12:32.8867      Call Duration 00:00:00.0000
> Status: 0xBFFF0000 (VI_ERROR_SYSTEM_ERROR)

Any insight or lines of investigation would be greatly appreciated.

Thank you for your time.

[psuedonym]

_mbSession  is protected variable in the class FactoryInterface

Is SendCommand a member of the FactoryInterface class? I can't tell with the code snippet.

[runverzagt]

Yes, SendCommand is a member of FactoryInterface.

[runverzagt]

This is not the only com port device which I am connecting to through the VISA library. I have notice that my failure disappears when I do not connect to my Korad power supply, and the failure returns when I am connected to the power supply.

I should say that not connecting to the power supply is not an acceptable workaround. I need to be able to connect to both the power supply and the factory interface at the same time.

[psuedonym]

I am not sure how having another instrument is relevant.

Only one instrument can be connected to one serial port.

[runverzagt]

I narrowed down the relationship to the power supply. In a setup routine, a FactoryInterface object is created. Then, the power supply is used to power cycle the device which is connected through the FactoryInterface  object. After the device is powered up, I send it a command. This communication is where the error occurs. The error does not occur if no power cycle is done.

So my follow up question is: how does power cycling a device which has a live serial connection disrupt the serial connection? Do I have to "close" the connection before powering off the device, then "open" the connection after it is powered up? This is the experiment I will try next.