Filter
Top Products
Chapter 7 NI-488.2 Programming Techniques
NI-488.2 User Manual for Windows 7-18 www.natinst.com
The following example code configures a device for parallel polling
using traditional NI-488.2 calls. The device asserts DIO7 if its
ist
is 0.
In this example, the
ibdev
command opens a device that has a primary
address of 3, has no secondary address, has a timeout of 3 s, asserts
EOI with the last byte of a write operation, and has EOS characters
disabled.
The following call configures the device to respond to the poll on DIO7
and to assert the line in the case when its
ist
is 0. Pass the binary bit
pattern, 0110 0110 or hex 66, to
ibppc
.
#include "decl-32.h"
char ppr;
dev = ibdev(0,3,0,T3s,1,0);
ibppc(dev, 0x66);
If the GPIB interface configures itself for a parallel poll, you should
still use the
ibppc
function. Pass the interface index or an interface
unit descriptor value as the first argument in
ibppc
. Also, if the
individual status bit (
ist
) of the interface needs to be changed, use the
ibist
function.
In the following example, the GPIB interface is to configure itself to
participate in a parallel poll. It asserts DIO5 when
ist
is 1 if a parallel
poll is conducted.
ibppc(0, 0x6C);
ibist(0, 1);
2. Conduct the parallel poll using
ibrpp
and check the response for a
certain value. The following example code performs the parallel poll
and compares the response to hex 10, which corresponds to DIO5. If
that bit is set, the
ist
of the device is 1.
ibrpp(dev, &ppr);
if (ppr & 0x10) printf("ist = 1\n");
3. Unconfigure the device for parallel polling with
ibppc
. Notice that
any value having the parallel poll disable bit set (bit 4) in the bit pattern
disables the configuration, so you can use any value between hex 70
and 7E.
ibppc(dev, 0x70);