New NI-488M Functions
Appendix A
AT-GPIB/NI-488M/AT&T UNIX
A-4
© National Instruments Corp.
IBLINES(3)
board only
IBLINES(3)
Purpose
Return the status of the GPIB control lines.
Synopsis
#include <sys/ugpib.h>
iblines (ud, clines)
int ud;
int *clines
Description
ud
is a board descriptor. A valid mask is returned along with the
GPIB control line state information in
clines
. The low-order
byte (bits 0 through 7) of
clines
contains a mask indicating the
capability of the GPIB interface board to sense the status of each
GPIB control line. The next-order byte (bits 8 through 15)
contains the GPIB control line state information. Bits 16 through
31 are undefined. The pattern of the
defined bytes is as follows:
7
6
5
4
3
2
1
0
EOI
ATN
SRQ
REN
IFC
NRFD
NDAC
DAV
To determine if a GPIB control line is asserted, first check the
appropriate bit in the lower byte to determine if the line can be
monitored. If the bit can be monitored (indicated by a 1 in the
appropriate bit position), check the corresponding bit in the upper
byte. If the bit is set (1), the corresponding control line is asserted.
If the bit is clear (0), the control line is unasserted.
For
iblines
to return valid data, a well-behaved IEEE-488 bus
must exist. A well-behaved IEEE-488 bus is a bus in which all
attached devices are following the IEEE-488 specification.
