National Instruments NI-488.2 ユーザーズマニュアル

© National Instruments Corporation

You can use the device-level traditional NI-488.2 call 

ibrsp

 to conduct 

a serial poll. 

ibrsp

 conducts a single serial poll and returns the serial poll 

response byte to the application. If automatic serial polling is enabled, the 
application can use 

ibwait

 to suspend program execution until RQS 

appears in the status word, 

ibsta

. The program can then call 

ibrsp

 to 

obtain the serial poll response byte.

The following example shows you how to use the 

ibwait

 and 

ibrsp

 

functions in a typical SRQ servicing situation when automatic serial polling 
is enabled:

#include "ni488.h"

char GetSerialPollResponse ( int DeviceHandle )

{

char SerialPollResponse = 0;

ibwait ( DeviceHandle, TIMO | RQS );

if ( ibsta & RQS )  {

printf ( "Device asserted SRQ.\n" );

/* Use ibrsp to retrieve the serial poll response. */

ibrsp ( DeviceHandle, &SerialPollResponse );

}

return SerialPollResponse;

}

The NI-488.2 software includes a set of multi-device NI-488.2 calls that 
you can use to conduct SRQ servicing and serial polling. Calls pertinent 
to SRQ servicing and serial polling are 

AllSpoll

, 

ReadStatusByte

, 

FindRQS

, 

TestSRQ

, and 

WaitSRQ

. Following are descriptions of each of 

the calls:

•

AllSpoll

 can serial poll multiple devices with a single call. It places 

the status bytes from each polled instrument into a predefined array. 
Then, you must check the RQS bit (bit 6 or hex 40) of each status byte 
to determine whether that device requested service.

•

ReadStatusByte

 is similar to 

AllSpoll

, except that it only serial 

polls a single device. It is similar to the device-level NI-488.2 

ibrsp

 

function.