Measurement Computing Personal488 rev.3.0 For DOS & Windows 3.Xi - Manual (Page 251)

10F. Visual Basic II. SOFTWARE GUIDES - 10. Driver488/W31
II-236 Personal488 User’s Manual, Rev. 3.0
always available within Driver488/W31, is used to clone a new device called ADC using the
MakeDevice command. GetError is then called to clear the internal error registered within
Driver488/W31. Lastly, the IEEE bus address 14 is assigned to the ADC .
If other devices were needed for the application at hand, they could either be defined in the startup
configuration for Driver488/W31 or they could be created “on the fly” from the application:
adc2% = MakeDevice(adc, “ADC2")
rv% = BusAddress(adc2, 10, -1)
The new device ADC2 is configured to reside at a different bus address so that the two devices may be
distinguished. There is one other important difference between ADC and ADC2 at this point. ADC2 is a
temporary device; that is, as soon as the creating application closes, ADC2 ceases to exist. If our intent
were to create a device that could be accessed after this application ends, we must tell Driver488/W31
this:
rv%=KeepDevice (adc2)
After executing the above statement, ADC2 is marked as being permanent; that is, the device will not be
removed when the creating application exits. If we later wish to remove the device, however, we can
do so explicitly:
rv%=RemoveDevice (adc2)
Confirming Communications
With or without an open device handle, the application can, if desired, confirm communication with
Driver488/W31 via the Hello function:
rv% = Hello(ieee%, response)
mystring = “”
The function also fills in a string, from which information can be extracted if it is desirable to display
facts about the driver in use.
IEEE 488 Event Custom Control
The IEEE 488 Event Custom Control feature of Driver488/W31 allows a Visual Basic program to
respond to IEEE 488 bus events. This feature is represented by a tool icon in the toolbox containing
“488” within a double arrow which appears when the
IOTEVENT.VBX file is included in the Project
window. To begin this program from the VB File menu, select the tool icon and then select
IOTEVENT.VBX .
The IEEE 488 Event Custom Control has properties that correspond to IEEE 488
bus events that can be enabled or disabled. If an IEEE 488 Event Custom Control
property is enabled, the Visual Basic program will call a user written function
associated with the specified event when the event occurs. The IEEE 488 Event
Custom Control has two other properties: the
Handle property and the CtrlName
property. The Handle property specifies the device that the events describe. The
CtrlName property stores space for the name of an application text box. For more
information on CtrlName , refer to the topic “Dynamic Data Exchange (DDE)”
found later in this Sub-Chapter.
The IEEE 488 bus events that Driver488/W31 supports are shown in the following table:
IEEE 488 Event
Custom Control
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