Omega OMB-PER-488/W95, User Manual

Page: 54 / 144

48 API Command Reference Personal488 User's Manual For Windows95 and Windows NT
Abort
Syntax
INT WINAPI Abort(DevHandleT devHandle);
devHandle refers to either an IEEE 488 hardware interface or an external device. If
devHandle
refers to an external device, the
Abort
command will act on the
hardware interface to which the external device is attached.
Returns
-1 if error
Mode
SC or *SC
•
CA
Bus States
IFC, *IFC
(if
SC
)
ATN
•
MTA (if *SC
••
CA )
Example
errorflag = Abort(ieee);
See Also
MyTalkAddr, Talk, UnTalk
As the System Controller (
SC
), whether Driver488 is the Active Controller or not, the
Abort
command
causes the Interface Clear (
IFC
) bus management line to be asserted for at least 500 microseconds. By
asserting
IFC
, Driver488 regains control of the bus even if one of the devices has locked it up during a
data transfer. Asserting
IFC
also makes Driver488 the Active Controller. If a Non System Controller
was the Active Controller, it is forced to relinquish control to Driver488.
Abort
forces all IEEE 488
device interfaces into a quiescent state.
If Driver488 is a Non System Controller in the Active Controller state (
*SC
••
CA
), it asserts Attention
(
ATN
), which stops any bus transactions, and then sends its My Talk Address (
MTA
) to “Untalk” any
other Talkers on the bus. It does not (and cannot) assert
IFC
.