Agilent Technologies E2094S Guía de usuario descargar pdf (Pagina 77)

Programming with VISA 3

Agilent VISA User’s Guide 77

/* Print results */

printf ("Instrument identification string:

%s\n", buf);

/* Close session */

viClose (vi);

viClose (defaultRM);}

Example: Shared Lock This example shows a session gaining a

shared lock with the accessKey called lockkey. Other sessions can now

use this accessKey in the requestedKey parameter of the viLock

function to share access on the locked resource. This example then

shows the original session acquiring an exclusive lock while

maintaining its shared lock.

When the session holding the exclusive lock unlocks the resource via

the viUnlock function, all the sessions sharing the lock again have all

the access privileges associated with the shared lock.

/* lockshr.c

This example program queries a GPIB device for

an identification string and prints the results.

Note that you must change the address. */

#include <visa.h>

#include <stdio.h>

void main () {

ViSession defaultRM, vi;

char buf [256] = {0};

char lockkey [256] = {0};

/* Open session to GPIB device at address 22 */

viOpenDefaultRM (&defaultRM);

viOpen (defaultRM, "GPIB0::22::INSTR",

VI_NULL,VI_NULL,&vi);

/* acquire a shared lock so only this process

and processes that we know about can access

this resource */

viLock (vi, VI_SHARED_LOCK, 2000, VI_NULL,

lockkey);

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Agilent Technologies E2094S Guía de usuario Pagina 77