Measurement Computing Personal488 rev.3.0 For DOS & Windows 3.Xi - Manual (Page 226)

II. SOFTWARE GUIDES - 10. Driver488/W31 10E. C Languages
Personal488 User’s Manual, Rev. 3.0 II-211
/* Open Driver488/W31 */
if ((ieee=OpenName(“IEEE”))<0) {
MessageBox(hWndDlg,(LPSTR)"Cannot initialize IEEE system",
NULL,MB_OK);
EndDialog(hWndDlg, TRUE);
return TRUE;
}
/* Open or create the device named ADC */
Error(ieee, OFF);
switch (adc=OpenName(“ADC”)) {
case -2:
MessageBox(hWndDlg,(LPSTR)"ADC device already open",NULL,
MB_OK);
EndDialog(hWndDlg, TRUE);
return TRUE;
case -1:
/* Create the device ADC by copying the default device WAVE*/
switch (devhandle=OpenName(“WAVE”)) {
case -2:
MessageBox(hWndDlg,(LPSTR)"WAVE device already
open",NULL,MB_OK);
EndDialog(hWndDlg, TRUE);
return TRUE;
case -1:
MessageBox(hWndDlg,(LPSTR)"Cannot open WAVE
device",NULL,MB_OK);
EndDialog(hWndDlg, TRUE);
return TRUE;
default:
break;
}
if ((adc=MakeDevice(devhandle, “ADC”))) {
MessageBox(hWndDlg, (LPSTR)"Cannot create ADC device", NULL,
MB_OK);
EndDialog(hWndDlg, TRUE);
return TRUE;
}
Close(devhandle);
break;
default:
break;
}
GetError(ieee, textstr);
BusAddress(adc, 14, -1);
If the ADC was not configured within Driver488/W31, it can be optionally created “on the fly”, as
shown above. First Error was used to turn OFF automatic error reporting so that our application can
trap the error instead. If opening the name ADC failed, the handle of the device IEEE , which is 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")
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
was to create a device that could be accessed after this application ends, we must tell Driver488/W31
this:
KeepDevice (adc2)
After executing the previous 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:
RemoveDevice (adc2)