Try/Catch on IOException isn't catching an IOException

General
1

Maybe I’m not doing this correctly but…

In the opening event of my app’s main window, I call a method inside a utility module, that tries to open a serial connection automatically:

//Select the serial port
SelectedSerialPort = SerialDevice.WithName(Settings.SerialPortName)

//Set up Serial Port Parameters
wMainWindow.DetanglerSerial.Device = SelectedSerialPort
wMainWindow.DetanglerSerial.Baud = 9600
wMainWindow.DetanglerSerial.Bits = 8
wMainWindow.DetanglerSerial.Parity = SerialConnection.Parities.None
wMainWindow.DetanglerSerial.StopBit = SerialConnection.StopBits.One

if RouterConnectionState = false then 
  // Connect to the serial device
  Try
    wMainWindow.DetanglerSerial.Connect
  Catch error As IOException
    System.Beep
    MessageBox("The selected serial device could not be opened.")
  End Try
End If

This works fine when the serial device is present. However, when I unplug the device from the computer and run it it’s failing inside the try statement with an IOException (error 2) and dropping me to the debugger. Shouldn’t I get a beep and a message telling me it wouldn’t work?

2

If you have the ‘break on exceptions’ during debugging the system will break/stop there.

You can change that option or just continue debugging so it can jump to the exception section.

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1 Like
3

Thanks. That was it!

4

You can also add
#pagma BreakOnExceptions False
try
catch
end try
#pagma BreakOnExceptions true

This will allow the try catch code to work without breaking, then turn back on the break for the code after.

3 Likes
5

I have seen recommendations to use #Pragma BreakOnExceptions Default at the end instead of True.

Edit: Rick explains why.

3 Likes
6

Yep. After disabling the break to process something, you probably want to return to your “global scope” choice, set in the Project menu, instead of just forcefully enabling it.