Re: Suppress error dialogs when checking if scanner connected

Hi I'm using the following code to detect if a scanner is connected when my application starts up:

	   try {
                if (TwainSession.IsAvailable(this)) {
                    TwainSession tw = new TwainSession();                    
                    tw.Startup(this, "", "", "", "");
                    TwainCapability tc = tw.GetCapability(TwainCapabilityType.DeviceOnline, TwainGetCapabilityMode.GetCurrent);
			// set app vars here based on result
                    tw.Shutdown();
                    tw = null;
                }
            }

            catch {}

The problem is, if the scanner is not connected, LeadTools shows an error dialog that needs to be OKd before an exception is thrown. Is there anyway to suppress the error dialogs? Or is there another way to do this that won't show an error dialog?

Thanks,

Adam

Unfortuneatly, this feature is not well supported in many devices.  Also, you are unable to ask if the device is online until you have actually opened the device, which kind of defeats the purpose of the feature.  This is part of the TWAIN specification and doing some searching about CAP_DEVICEONLINE yielded no easy way around this issue.

I would recommend disabling all scanning features when the exception is thrown and enable some option to select the TWAIN source.  When the user later selects a TWAIN source, perform the same check only enabling scanning options when tc.OneValueCapability.Value is true.

Thanks for your response..So there's no way to suppress the error dialogs?

I searched through all of our help files and was unable to find a return code of -4501.  As far as I can tell this is a TWAIN error dialog and there is no way to suppress it.