How do I software trigger the barcode scanner of a handheld device?

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Hello everybody,

I am currently writing an application for Panasonic's TOUGHPAD FZ-E1 and I have problems software triggering the barcode scanner. I know this is possible because the demo app that came with it does that.
My code is written in C# according to the Microsoft documentation provided here
https://msdn.microsoft.com/en-us/library/dn792056(v=winembedded.81).aspx[^]

The app crashes when I call this method:

private async void SoftwareTrigger_Click(object sender, RoutedEventArgs e)
{
    if (scanner.Capabilities.IsSoftwareTriggerSupported)
    {
        await claimedScanner.StartSoftwareTriggerAsync();
    }
}

The code compiles, but when I test it on device the app crashes saying that IsSoftwareTriggerSupported and StartSoftwareTriggerAsync() are not found.
I carefully followed all the steps in the documentation and I don't think I missed something.

If someone has any idea how to achieve my goal please let me know.

Thank you,
Raul

Posted 7-Feb-15 8:02am

Hatzy

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BillWoodruff 8-Feb-15 4:26am

You need to confirm that this device supports those commands, or conforms to a standard where those commands are guaranteed to be supported. For that, you will need to consult the manufacturer's documentation and/or technical support.

Or, you might get lucky and find someone else on the web who has a fix for this.

[no name] 9-Feb-15 1:27am

This is how you check if the software trigger is supported on the device
scanner.Capabilities.IsSoftwareTriggerSupported
The problem is that this crashes too and it shouldn't. It acts like the deploy operation does not copy the right assembly because at runtime the property does not exist.

Sinisa Hajnal 9-Feb-15 2:17am

It acts as if your scanner variable is of the object type that does NOT have those methods and properties. Put a breakpoint and see runtime type - maybe you just have to cast generic IReader object to particular type.

Check the demo code if available and re-check the documentation.

[no name] 9-Feb-15 2:48am

This happens before reading from the scanner.
The BarcodeScanner objects are the same (compile time and runtime). The BarcodeScannerCapabilities are different.

If I go to definition I see these properties

public sealed class BarcodeScannerCapabilities
{
public bool IsImagePreviewSupported { get; }
public bool IsSoftwareTriggerSupported { get; }
public bool IsStatisticsReportingSupported { get; }
public bool IsStatisticsUpdatingSupported { get; }
public UnifiedPosPowerReportingType PowerReportingType { get; }
}

At runtime IsSoftwareTriggerSupported is missing from my object. The capabilities object has only the other 4 properties

scanner = await BarcodeScanner.GetDefaultAsync();
BarcodeScannerCapabilities capabilities = (BarcodeScannerCapabilities)scanner.Capabilities;

Sinisa Hajnal 9-Feb-15 3:41am

And what is runtime type of capabilities object? Does that differ? Also, ensure that you have latest libraries referenced in your References...it sometimes happens that you take one older library that doesn't support things that came later (obviously) - so check DLL versions.

[no name] 9-Feb-15 5:01am

The runtime type of capabilities object does not differ from compile time.
The references were automatically added by Visual Studio when I created the solution (.Net for Windows Store apps and Windows Phone 8.1).
I don't know how what assembly versions are deployed on device. Is there a way to look inside an .appx package?

Update:
On simulator everything works as expected.
Device is running Windows Embedded 8.1 Handheld and is up to date.

Anant Ashrit 12-Dec-17 4:05am

I am also using the same device and facing the same problem. Any update on this Raul ?

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