Measurement Computing Personal488 rev.3.0 - Manual (Page 69)

Personal488 for Windows 95/98/Me/NT/2000 04-10-01 API Reference 6-1
API Reference 6
This chapter contains the API command reference for Driver488/W95 and Driver488/WNT, using the
C language. The following commands are presented in alphabetical order for ease of use.
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
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 100 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 .