Experimental Physics and
Industrial Control System

One thing I did not made clear in the previous email: the idea is that the

device has to respond to the message. 

Ahhh...

O.K.  a custom conversion routine is not adequate in this case.

My first idea was to use the GBIBREAD operation for that, but this type has

only got a conversion routine for the reply. I had taken a look to the

GPIBCVTIO type, but this is not a query->response construction.

Yes it is.  GPIBCVTIO is completely general-purpose.  Nick DiMonte's Tektronix oscilloscope support uses GPIBCVTIO.  I've included some sections of his code.

Here's an example of a GPIBCVTIO routine which sends commands and gets replies.

/* 180 : read ethernet name SI */

         {&DSET_SI, GPIBCVTIO, IB_Q_HIGH, NULL, NULL, 0, 100,

          getEthernetName, 0, 0, NULL, NULL, NULL},

static int

getEthernetName(struct gpibDpvt *pdpvt, int P1, int P2, char **P3)

{

    struct stringinRecord *psi= (struct stringinRecord *) (pdpvt->precord);

    asynOctet *pasynOctet = pdpvt->pasynOctet;

    void *asynOctetPvt = pdpvt->asynOctetPvt;

    int j;

    size_t ntrans;

    char cbuf[300];

    char make[12], model[12];

    char netName[40];

    if ((pasynOctet->write(asynOctetPvt,pdpvt->pasynUser,"*IDN?",

                                sizeof"*IDN?" - 1,&ntrans) != asynSuccess)

     || (pasynOctet->read(asynOctetPvt,pdpvt->pasynUser,cbuf,

                              sizeof cbuf - 1,&ntrans,NULL) != asynSuccess)) {

        recGblSetSevr(psi, READ_ALARM, INVALID_ALARM);

        return -1;

    }

    cbuf[ntrans] = '\0';   /* Null-terminate reply message */

    /* do the checks in cbuf and optionally send the "ETHERNET:NAME?"

       using the write/read commands like above */

    if (( j = sscanf(cbuf, "%11[^,],%11[^,]", make, model)) != 2){

      printf("Scope ERROR: Scope ID scanned %d, min 2 needed. ID string = \n %s \n"

         , j, cbuf);

      return -1;

    }

    if(TDS3000Debug) {

      printf("cbuf = %s\n",cbuf);

      printf("make = %s\n",make);

      printf("model = %s\n",model);

      printf("model[8] = %c\n",model[8]);

    }

    if ( model[8] == 'B' || strstr(cbuf,"TDS3EM") != NULL ){ /* has ethernet option */

      if ((pasynOctet->write(asynOctetPvt,pdpvt->pasynUser,"ETHER:NAME?",

                                sizeof"ETHER:NAME?" - 1,&ntrans) != asynSuccess)

           || (pasynOctet->read(asynOctetPvt,pdpvt->pasynUser,cbuf,

                                  sizeof cbuf - 1,&ntrans,NULL) != asynSuccess))

      {

        recGblSetSevr(psi, READ_ALARM, INVALID_ALARM);

        return -1;

      }

      cbuf[ntrans] = '\0';   /* Null-terminate reply message */

      sscanf(cbuf, "%39[^\n\r]",netName);

    }

    else {

      sscanf(cbuf, "%18[^\n\r]",netName);

    }

    strcpy(psi->val,netName);

    return 0;

}

Here's an example that handles binary data.  The readArbitraryBlockProgramData routine is part of the ASYN package.  Have a look at it to see how arbitraty 8-bit data can be transferred.

/* 19 : read waveform : WF */

        {&DSET_WF, GPIBCVTIO, IB_Q_LOW, "DAT:SOU CH1;:WAVFRM?",

            "%lf", 0, 32000, convertData, 0 ,0, NULL, NULL, NULL},

static int convertData(pdpvt, P1, P2, P3)

  struct gpibDpvt *pdpvt;

  int P1;

  int P2;

  char **P3;

{

  double        xIncr, xZero, yMult, yZero, yOff;

  int byte, bits, length, ptOff, width;

  char encode[20], binFmt[20], byteOr[20], idString[80], ptFmt[20], xUnit[20], yUnit[20];

  int len, i;

  size_t ntrans;

  struct waveformRecord *pwf= (struct waveformRecord *) (pdpvt->precord);

    gpibCmd *pgpibCmd = gpibCmdGet(pdpvt);

    asynOctet *pasynOctet = pdpvt->pasynOctet;

    void *asynOctetPvt = pdpvt->asynOctetPvt;

    if ((pasynOctet->write(asynOctetPvt,pdpvt->pasynUser,pgpibCmd->cmd,

                                      strlen(pgpibCmd->cmd),&ntrans) != asynSuccess)

     || (pdevSupportGpib->readArbitraryBlockProgramData(pdpvt) <= 0)) {

        recGblSetSevr(pwf, READ_ALARM, INVALID_ALARM);

        return -1;

    }

  if (sscanf(pdpvt->msg, "%d;%d;%19[^;];%19[^;];%19[^;];%d;%79[^;];%19[^;];"

                         "%lg;%d;%lg;%19[^;];%lg;%lg;%lg;%19[^;];#%1d%n",

         &byte, &bits, encode, binFmt, byteOr, &length, idString, ptFmt,

         &xIncr, &ptOff, &xZero, xUnit, &yMult, &yZero, &yOff, yUnit, &width, &i

            ) != 17) {

    recGblSetSevr(pwf, READ_ALARM, INVALID_ALARM);

    return -1;

  }

  if(TDS3000Debug) {

      printf("%p, index=%d\n", (unsigned char *)&pdpvt->msg[0],i);

      printf("byte- %d, bits- %d, encode- %s, binFmt- %s, byteOr-  %s\n",

              byte, bits, encode, binFmt, byteOr);

      printf("length- %d, ptFmt- %s\n",

              length, ptFmt);

      printf("xIncr- %g\nptOff- %d\nxZero- %g\nyMult- %g\nyZero- %g\nyOff- %g\n"              , xIncr, ptOff, xZero, yMult, yZero, yOff);

  }

  i += width; /* I should be pointing to the first data byte now */

  /* Copy waveform data from response buffer to waveform record */

  if(P1) {

      printf("%p, index=%d\n", (void *)&pdpvt->msg[0], i);

      printf("ptFmt - %s, length - %d\n", ptFmt, length);

      len = P1;   /* if P1 is non-zero, use it as length */

  }

  else {

      len = length;

  }

  memcpy((char *)pwf->bptr, (char *)&pdpvt->msg[i], len*byte);

  pwf->nord=len;

  return(0);

}

-- 

Eric Norum <[email protected]>

Advanced Photon Source

Argonne National Laboratory

(630) 252-4793