B&B Electronics 4 Channel Input Buffer Board SDAIBB Instrukcja Użytkownika Pobierz pdf (Strona 51)

Documentation Number UD128A8D4602 Manual Chapter 5 47

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Handling Device Changes – USB Hot Plug/Unplug

The OnChange Event - After BDaq.BBDaqEnum is created, any

change in the devices connected (plugging in a new device or

unplugging a connected device) causes an OnChange event to

occur. You can trigger on this event to check available devices,

change which devices you are addressing or to detect a new device.

Private Sub Connected_OnChange()

‘ \ Cleanup Variables, Check available Devices,

‘ \ Notify the user of the change,

‘ \ Change the device being addressed, configure, etc.

End Sub

If one set of test connections is on the first device installed as

“DAQ1” and another set of connections is on “DAQ2” and one is

unplugged, we want to set the software to access only the device

remaining.

We can use the OnChange event to trigger checking what devices

are connected, and which tests to perform.

EnableTest1 is a subroutine that configures the I/O for “DAQ1” and

enables the user to start Test 1.

EnableTest2 is a subroutine that configures the I/O for “DAQ2” and

enables the user to start Test 2.

Private Sub Connected_OnChange()

Dim Device as Variant

Set Device1 = Nothing

Set Device2 = Nothing

If Connected.Devices.Count = 0 then

‘ \ Inform user and and stop acess until another connected

Exit Sub

End If

‘ \ If at least one device, check which it is – select test

For Each Device In Connected.Devices

If Device.Name = "DAQ1" Then

Set Device1 = Device

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B&B Electronics 4 Channel Input Buffer Board SDAIBB Instrukcja Użytkownika Strona 51