Klaus Kragelund wrote:
> Hi all
>
> Sorry - this post is a bit long.
>
> I'm working on a testsystem comprised of a couple of DMMs (HP34401A), and
> some other instruments. My problem is that a have a Function Panel for the
> DMMs, but I also have a power supply that doesn't have any instrument driver
> - that is it will only understand SCPI commands.
I am not overly familiar with CVI, but I don't think that a FP and SCPI are mutually
exclusive. I have seen FPs for instruments that use SCPI commands to talk to devices.
>
>
> Furthermore I have written a runtime compiler so that the CVI program doesn't
> need to be changed if I change the testprocedure. One of my compilercommands
> looks like this:
>
> DCSupply1.SetVoltage=10.03;
>
> These are my questions:
>
> x The solution to the problem of the powersupply only understanding SCPI
> commands could be to build a driver from the CVI wizard?.
>
Yes this can be done easily, and may be the way the DMMs were done. All FPs for
GPIB equipment eventually boil down to sending a string to the GPIB card which
addresses the device and sends the string to it. SCPI is nothing more than an attempt
to standardize what the strings mean.
>
> x In order not have to write a lot of compiler commands I have narrowed the
> language into some general commands, and the more specific commands like
> setting the resolution of the DMMs will be performed by using a SCPI command.
> Is it possible to run both with an instrument driver and a SCPI command simutaniously.
You can do both, but you can only have one at a time talking to the GPIB / device.
If the FPs use IVI you may have interactions that you did not anticipate. Some IVI
drivers
do state caching and if you change something without the use of the IVI driver it's state
information MAY be incorrect.
>
>
> x This is simple: How do I transmit a SCPI command to a specific instrument
> ? Is the ibwrt command OK? With respect to the previous question - can this
> be issued in a interlaced fashion ?
You could use the ibwrt, though this is a low level function for the GPIB device,
if by interlaced you mean use the FP and then send a low level ibwrt, yes you can
but with the same problems that you will face above.
If I have made some sort of error in these comments would someone please let me know.
Kevin Kent
