Measurement Computing Personal488 rev.3.0 - Manual (Page 87)

Personal488 for Windows 95/98/Me/NT/2000 04-10-01 API Reference 6-19
FindListeners
Syntax INT WINAPI FindListeners(DevHandleT devHandle, BYTE primary,
LPWORD listener, DWORD limit);
devHandle refers to either an IEEE 488 interface or an external device. If devHandle
refers to an external device, then the FindListeners command acts on the
hardware interface to which the external device is attached.
primary is the primary IEEE 488 bus address to check.
listener is a pointer to a list that contains all Listeners found on the specified interface
board. You must allocate enough memory to accommodate all of the possible Listeners
up to the limit that he specified.
limit is the maximum number of Listeners to be entered into the Listener list.
Returns -1 if error
otherwise, the number of Listeners found on the interface
Bus States ATN
•MTA, UNL, LAG
Example WORD listeners[5];
errorcode = FindListeners(ieee,10,listeners,5);
See Also CheckListener, BusAddress, Status
The FindListeners command finds all of the devices configured to Listen at the specified primary
address on the IEEE 488 bus. The command first identifies the primary address to check and returns the
number of Listeners found and their addresses. Then, it fills the user-supplied array with the addresses of
the Listeners found. The number of Listeners found is the value returned by the function. The returned
values include the secondary address in the upper byte, and the primary address in the lower byte. If there
is no secondary address, then the upper byte is set to
255 ; hence, a device with only a primary address of
16 and no secondary address is represented as 0xFF10 or -240 decimal.