USBDemo, something to learn USB a little bit

[Darrel Taylor]

Ok i will use Darrel´s exe program.

Thank You!<hr>
Looking at the VB side of USBDemo

Public Sub OnPlugged(ByVal pHandle As Long)
    '
    '   A HID device has been plugged in,
    '   check if it's the right one, and enable the form LED (top left)
    '
    Dim DeviceHandle As Long
    Dim VendorName As String * 15
    Dim ProductName As String * 15
    
    If hidGetVendorID(pHandle) = VendorID And hidGetProductID(pHandle) = ProductID Then ' Good one?
        '
        '   get the device handle
        '   =====================
        DeviceHandle = hidGetHandle(VendorID, ProductID)
        '
        '   Get the vendor and product name from the handle
        '   ===============================================
        hidGetVendorName DeviceHandle, VendorName, 255
        hidGetProductName DeviceHandle, ProductName, 255
        '
        '   Enable the LED and display device information
        '   VendorName and ProductName
        '   =============================================
        imgON.Visible = True
        lVendorName.Caption = VendorName
        lProductName.Caption = ProductName
        End If
End Sub

Using the line shown in red, anytime a device is plugged in with the same Vendor/Product ID, it will forget about the last device and start using the new one.

To get around that, you need to check further to make sure it's the device you want to talk to. And, for that, you need to search through the HID Device list.

Again, I don't do VB, so the syntax is most probably wrong. But ...<hr>
The function hidGetItemCount returns the number of HID devices in the List.
Then hidGetItem(Index) returns the handle of the item in the list that's specified by Index (0 to count-1).

You can get the info about that device by requesting each field.
Vendor = hidGetVendorID(handle)
Product = hidGetProductID(handle)
Serial = hidGetSerialNumber(handle)

Now if everything matches, you know you have the right one. If not, keep searching through the list.

If you're not using the Serial Number, you'll need to send/receive something to the device to figure out if it's the correct one.

Is that any help?
I'll keep trying if not.
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