National Instruments NI-488.2 - Manual (Page 101)

Appendix B Status Word Conditions
© National Instruments Corporation B-5 NI-488.2 User Manual
LACS (brd)
LACS indicates whether the GPIB interface is addressed as a Listener.
LACS is set whenever the GPIB interface detects that its listen address
(and secondary address, if enabled) has been sent either by the GPIB
interface itself or by another Controller. LACS is also set whenever the
GPIB interface shadow handshakes as a result of the
ibgts function.
LACS is cleared whenever the GPIB interface detects the Unlisten (UNL)
command, its own talk address, Interface Clear (IFC), or that the
ibgts
function has been called without shadow handshake.
DTAS (brd)
DTAS indicates whether the GPIB interface has detected a device trigger
command. DTAS is set whenever the GPIB interface, as a Listener, detects
that the Group Execute Trigger (GET) command has been sent by another
Controller. DTAS is cleared on any call immediately following an
ibwait
or ibnotify call, if the DTAS bit is set in the ibwait mask parameter.
DCAS (brd)
DCAS indicates whether the GPIB interface has detected a device clear
command. DCAS is set whenever the GPIB interface detects that the
Device Clear (DCL) command has been sent by another Controller, or
whenever the GPIB interface as a Listener detects that the Selected Device
Clear (SDC) command has been sent by another Controller.
If you use the ibwait or ibnotify function to wait for DCAS and the
wait is completed, DCAS is cleared from ibsta after the next NI-488.2
call. The same is true of reads and writes. If you call a read or write function
such as
ibwrt or Send , and DCAS is set in ibsta , the I/O operation is
aborted. DCAS is cleared from ibsta after the next NI-488.2 call.