Omega OMB-PER-488/W95, User Manual

Page: 59 / 144

Personal488 User's Manual For Windows 95 and Windows NT API Command Reference 53
CheckListener
Syntax
INT WINAPI CheckListener(DevHandleT devHandle, BYTE primary,
BYTE secondary);
devHandle
refers to either an IEEE 488 hardware interface or an external device. If
devHandle refers to an external device, the CheckListener command acts on
the hardware interface to which the external device is attached.
primary is the primary bus address to check for a Listener ( 00 to 30 )
secondary is the secondary bus address to check for a Listener ( 00 to 31 ). For no
secondary address, a
-1
must be specified
Returns
-1 if error
otherwise it returns a 1 if a listener was found at the specified address, or a 0 if a listener
was not found at the specified address.
Mode
CA
Bus States
ATN
••
UNL, LAG, (check for NDAC asserted)
Example
result = CheckListener(ieee,15,4);
if (result == 1)
{
printf(“Device found at specified address.\n”);
}
if (result == 0)
{
printf(“Device not found at specified address.\n”);
}
See Also
FindListener, BusAddress
The
CheckListener
command checks for the existence of a device on the IEEE 488 bus at the
specified address.