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usb-6009

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This commit is contained in:
Mike Phares
2024-11-01 11:47:29 -07:00
commit ebbc16ee6a
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143
NI-VISA/Examples/C/USB/RdWrtUSBTMC.c Normal file
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/********************************************************************/
/* Read and Write to a USBTMC Instrument */
/* */
/* This code demonstrates sending synchronous read & write commands */
/* to an USB Test & Measurement Class (USBTMC) instrument using */
/* NI-VISA */
/* The example writes the "*IDN?\n" string to all the USBTMC */
/* devices connected to the system and attempts to read back */
/* results using the write and read functions. */
/* */
/* The general flow of the code is */
/* Open Resource Manager */
/* Open VISA Session to an Instrument */
/* Write the Identification Query Using viWrite */
/* Try to Read a Response With viRead */
/* Close the VISA Session */
/********************************************************************/
#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
/* Functions like strcpy are technically not secure because they do */
/* not contain a 'length'. But we disable this warning for the VISA */
/* examples since we never copy more than the actual buffer size. */
#define _CRT_SECURE_NO_DEPRECATE
#endif
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "visa.h"
static ViSession defaultRM;
static ViSession instr;
static ViUInt32 numInstrs;
static ViFindList findList;
static ViUInt32 retCount;
static ViUInt32 writeCount;
static ViStatus status;
static char instrResourceString[VI_FIND_BUFLEN];
static unsigned char buffer[100];
static char stringinput[512];
int main(void)
{
int i;
/*
* First we must call viOpenDefaultRM to get the manager
* handle. We will store this handle in defaultRM.
*/
status=viOpenDefaultRM (&defaultRM);
if (status < VI_SUCCESS)
{
printf ("Could not open a session to the VISA Resource Manager!\n");
exit (EXIT_FAILURE);
}
/* Find all the USB TMC VISA resources in our system and store the */
/* number of resources in the system in numInstrs. */
status = viFindRsrc (defaultRM, "USB?*INSTR", &findList, &numInstrs, instrResourceString);
if (status < VI_SUCCESS)
{
printf ("An error occurred while finding resources.\nHit enter to continue.");
fflush(stdin);
getchar();
viClose (defaultRM);
return status;
}
/*
* Now we will open VISA sessions to all USB TMC instruments.
* We must use the handle from viOpenDefaultRM and we must
* also use a string that indicates which instrument to open. This
* is called the instrument descriptor. The format for this string
* can be found in the function panel by right clicking on the
* descriptor parameter. After opening a session to the
* device, we will get a handle to the instrument which we
* will use in later VISA functions. The AccessMode and Timeout
* parameters in this function are reserved for future
* functionality. These two parameters are given the value VI_NULL.
*/
for (i=0; i<numInstrs; i++)
{
if (i > 0)
viFindNext (findList, instrResourceString);
status = viOpen (defaultRM, instrResourceString, VI_NULL, VI_NULL, &instr);
if (status < VI_SUCCESS)
{
printf ("Cannot open a session to the device %d.\n", i+1);
continue;
}
/*
* At this point we now have a session open to the USB TMC instrument.
* We will now use the viWrite function to send the device the string "*IDN?\n",
* asking for the device's identification.
*/
strcpy (stringinput,"*IDN?\n");
status = viWrite (instr, (ViBuf)stringinput, (ViUInt32)strlen(stringinput), &writeCount);
if (status < VI_SUCCESS)
{
printf ("Error writing to the device %d.\n", i+1);
status = viClose (instr);
continue;
}
/*
* Now we will attempt to read back a response from the device to
* the identification query that was sent. We will use the viRead
* function to acquire the data. We will try to read back 100 bytes.
* This function will stop reading if it finds the termination character
* before it reads 100 bytes.
* After the data has been read the response is displayed.
*/
status = viRead (instr, buffer, 100, &retCount);
if (status < VI_SUCCESS)
{
printf ("Error reading a response from the device %d.\n", i+1);
}
else
{
printf ("\nDevice %d: %*s\n", i+1, retCount, buffer);
}
status = viClose (instr);
}
/*
* Now we will close the session to the instrument using
* viClose. This operation frees all system resources.
*/
status = viClose (defaultRM);
printf ("Hit enter to continue.");
fflush (stdin);
getchar();
return 0;
}