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46 VXI Programming Using the IEEE 1394 Serial Bus Chapter 3
// set the trigger source
iprintf(e1412, "TRIG:SOUR TTLT4\n");//trigger line 4
// set the sample count
iprintf(e1412, "SAMP:COUN 10\n");// 10 readings
// initiate the multimeter
iprintf(e1412, "INIT\n");
printf("Press ’Enter’ to trigger the voltmeter\n");
getchar ();
// output a trigger pulse on the E8491A ’Trig Out’ connector, the
// trigger is then input to the ’Trig In’ connector via a jumper wire
// and routed to TTL trigger line 4 which triggers the multimeter
ixtrig(e8491, I_TRIG_EXT0);
// fetch the readings once the trigger is received
ipromptf(e1412, "FETC?\n", "%,10lf", dcv_rdgs);
// display the readings
for (i=0; i<10; i++)
{
printf("%lf\n", dcv_rdgs[i]);
}
// close the device sessions
iclose(e8491);// close SICL interface session
iclose(e1412);// close SICL device session
}
Comments
1. For demonstation purposes, the trigger signal output from the ‘Trig Out’
port (ixtrig function) is routed to the ‘Trig In’ port using a jumper wire. The
signal is then routed to TTLTRG4 (ivxitrigroute function).
2. The external trigger routed to TTLTRG4 can also be routed to any or all
of the VXI backplane trigger lines.
3. When using the faceplate ‘Trig In’ and ‘Trig Out’ ports, notice that both
ports are specified using I_TRIG_EXT0.
In the program, ivxitrigroute(e8491s, I_TRIG_EXT0,
I_TRIG_TTL4)routes the trigger received on the faceplate ‘Trig In’ port
to backplane TTL trigger line 4. ixtrig(e8491s, I_TRIG_EXT0)
outputs a trigger pulse on the ‘Trig Out’ port which is connected by a
jumper wire to the ‘Trig In’ port.
4. This manual is included on the HP I_O Libraries CD. By viewing the
manual from the CD, you can cut and paste this program into your
development environment.