GPIB Instrument reads channel 1 when asked for channel

[Ian-Qld]

I have a HP3497A Data aquisition system connected via a NI PCI GPIB Controller. In LabwindowsCVI ver 5.0 I send the command to read channel 10 and the result that comes back is channel 11. What appears to happen is the HP close channel 10 then steps to 11 and sends the reading from 11 back to the program. Is this likely to be a GPIB board configuration problem or any other suggestions appreciated.

[Alan_L]

Ian-Qld,

What happens if you specify channel 9? Agilent enumerates their oscilloscopes' channels beginning with 0 (zero). In this case, sending a command to read from "10" would correspond to the 11th channel (if you start counting at 0).

Otherwise, if you are successfully able to send commands and receive responses, your board is most likely working perfectly.

Alan
Applications Engineer
National Instruments

[Ian-Qld]

Sparhawk,

The HP3497 also numbers from 0 and when I was asking for Channel 10 I was really asking for the 11th channel but getting the reading from channel 11 or the 12th channel. When I ran the spy program to monitor what was passing backwards and forwards between the GPIB card and the instrument I discovered that the command to read a channel was the only one I was using that also sent a IBTRG command. I've since been in and edited the Instrument Driver so it doesn't send the command and so far so good.

Now when I ask for channel 10 I get the reading for channel 10. Whether it is something peculiar to my setup or an error in the Instrument Driver I can't be sure but at least my problem has been solved.

Ian