Application takes data from devices connected via converter RS485/USB.

Hi.

My C# application takes data from devices connected via a converter RS485/USB.
However I get an error that does not know how to solve.
When the devices are turned off, my application freezes.
How can not lock the computer, but show a warning message to connect the devices or turn on and expects to receive data?

Thank you,
ocaccy
ocaccyAsked:
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tcssCommented:
Are you reading from the serial/RS485 port directly or via a supplier provided API?

Assuming you reading fromthe port, are you responding to the datareceived event or using a blocking read with the timeout set to infinate?.

Often with a USB device if the connected hardware if not powered (ie off) the virtual serial port does not exist. Are you checking for the port before opening it?

Hylton
0

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ocaccyAuthor Commented:
Hi,
snippet of the app:

public Form1()
        {
            InitializeComponent();
            
            LBL_message.Text = "";
            label4.Text = LBL_message.Text;

            int M_times = (Convert.ToInt32(nUD_KyuSoku.Value) + Convert.ToInt32(nUD_RyuSoku.Value) + Convert.ToInt32(nUD_Seiti.Value)) / 10;

            limpezadeAbertura();

            label127.Text = delta.ToString();
            preparando_lbl.Visible = false;
            button34.Visible = false;
            button5.Enabled = false;
            button33.Enabled = false;
            i_channel = Convert.ToInt32(nUD_Kesu.Value);

            GraphPane myPane02m = zed2mmccc.GraphPane;

            outputList_Initialize();

            Settings.Read();
            TopMost = Settings.Option.StayOnTop;

            // let form use multiple fonts
            origFont = Font;
            FontFamily ff = new FontFamily("Courier New");
            monoFont = new Font(ff, 8, FontStyle.Regular);
            Font = Settings.Option.MonoFont ? monoFont : origFont;

            CommPort com = CommPort.Instance;
            com.StatusChanged += OnStatusChanged;
            com.DataReceived += OnDataReceived;
            com.Open();

            rB_alarmON2.Checked = true;
            rB_alarmON1.Checked = true;
            rB_alarmOFF1.Checked = false;
            rB_alarmOFF2.Checked = false;
            limpezaInicial();
        }

        private DateTime inicio;

        int TickStart, intMode = 1;

        // shutdown the worker thread when the form closes
        protected override void OnClosed(EventArgs e)
        {
            CommPort com = CommPort.Instance;
            com.Close();

            base.OnClosed(e);
        }

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Thank you,
ocaccy
0
ocaccyAuthor Commented:
Hi.
The problem was solved.
I put a routine time to access the serial port.
At the end of this time or if the loop condition is satisfied; Closes the commport.
If do not receive data in time; closes the commport.
CommPort com = CommPort.Instance;
com.Close();
With that I had no more problems with the serial port.

Best regards,
ocaccy
0
tcssCommented:
Thank you for the feedback. Please you were able to solve it.
0
ocaccyAuthor Commented:
Thank you,
ocaccy
0
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