Well, it always help formulating ones problem into a question. Sometimes it get you out in corners of the documentation you didn't see the first round. So I solved my problem with the following snippets - if anyone else ends in the same alley as I. AM I doing to much, or should things be arranged differently? At least it works.
In the main program I have:
vierr = viOpenDefaultRM (&sesHandle);/* open a VISA session */
vierr = viOpen (sesHandle,
"USB0::0x0957:: .......::0::INSTR",
VI_NULL, VI_NULL, &agHandle);/* connect to the instrument */
bufferHandle = (ViBuf)malloc(MAX_CNT+1);/* I don't know what this is for ... MAX_CNT is 1024 */
vierr = viInstallHandler(agHandle, VI_EVENT_SERVICE_REQ, myCallback,
bufferHandle);/* Tell the driver what function to call on a SRQ event */
vierr = viPrintf (agHandle, "*CLS\n");/* Clear message queues on the Agilent */
vierr = viPrintf (agHandle, "STAT:ALARM:ENABLE 2\n"); /* Enable alarm 2 - the criterea to raise ALARM2 are set elsewhere */
vierr = viPrintf (agHandle, "*SRE 2\n"); /* Enable RSQ on Alarm register */
vierr = viEnableEvent(agHandle, VI_EVENT_SERVICE_REQ, VI_HNDLR, VI_NULL); /* Enable the driver to detect events */
The CallBack is defined prior to main as
ViStatus _VI_FUNCH myCallback(ViSession vi, ViEventType etype,
ViEvent eventContext, ViAddr userHandle)
{
ViStatus status;
ViUInt16 stb;
status = viReadSTB(vi, &stb); /* Read the stats bit */
if (stb & 2) { /* Check that it is an alarm - bit-mapping is device dependent */
/* do the actions for the alarm state */
}
vierr = viPrintf (agHandle, "*CLS\n"); /* Clear the status - this is necessary to be able to call again */
return VI_SUCCESS;
}
