Parallel Polling With Multi-Device Ni-488.2 Calls - National Instruments NI-488.2 User Manual

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Parallel Polling with Multi-Device NI-488.2 Calls

Complete the following steps to implement parallel polling the using
multi-device NI-488.2 calls. Each step contains example code.
1. Configure the device for parallel polling using the
unless the device can configure itself for parallel polling. The
following example configures a device at address 3 to assert data line 5
(DIO5) when its
#include "decl-32.h"
char response;
Addr4882_t AddressList[2];
/* The following command clears the GPIB. */
SendIFC(0);
/* The value of sense is compared with the ist bit
of the device and determines whether the data
line is asserted.*/
PPollConfig(0,3,5,1);
2. Conduct the parallel poll using
the response for a certain value. In the following example, because
DIO5 is asserted by the device if
(hex 10) in the response to determine the value of
PPoll(0, &response);
/* If response has bit 4 (hex 10) set, the ist bit
of the device at that time is equal to 1. If
it does not appear, the ist bit is equal to 0.
Check the bit in the following statement. */
if (response & 0x10) {
printf("The ist equals 1.\n");
}
else {
printf("The ist equals 0.\n");
}
3. Unconfigure the device for parallel polling using
shown in the following example. In this example, the
must appear at the end of the array to signal the end of the address list.
If is the only value in the array, all devices receive the parallel
NOADDR
poll disable message.
AddressList[0] = 3;
AddressList[1] = NOADDR;
PPollUnconfig(0, AddressList);
Chapter 7
value is 1.
ist
PPoll,
is 1, the program checks bit 4
ist
7-19
NI-488.2 Programming Techniques
PPollConfig
store the response, and check
.
ist
PPollUnconfig
NOADDR
NI-488.2 User Manual for Windows
call,
, as
constant