Can a GPIB board support 2 devices?

[Fan Zhang]

Hi Group,

I formerly using a GPIB board to control my multimeter. But now it seems like to me I need to use it to control another device, which is a temperature controller. I am wondering whether I am able to use the board to control two devices simutaneously. If you know, please help. Thanks.

Best,
Fan

--
Fan Zhang
Dept of Physics and Astronomy
University of Pennsylvania

-----" A journey of a thousand miles must begin with a single step."

[CraigGraham]

Yes, you can. Though a physicist of all people should be careful of the word
"simultaneously".

GPIB I think can do 31 instruments on one card. Communication at any one
time can only be with a single instrument at any one time, though various
system commands let you send, for example, a trigger signal to all the
instruments on the bus.

This should work fine for you if the temperature controller is autonomous-
i.e. you can set a temperature and leave it alone while it goes there,
periodically reading the temperature to check the progress. If it's a "dumb"
controller with PC based PID control you have to consider timing issues

----------------------

Fan Zhang wrote in message
news:96h8rm$qq1$1@netnews.upenn.edu...
Hi Group,

I for
merly using a GPIB board to control my multimeter. But now it seems
like to me I need to use it to control another device, which is a
temperature controller. I am wondering whether I am able to use the board to
control two devices simutaneously. If you know, please help. Thanks.

Best,
Fan

--
Fan Zhang
Dept of Physics and Astronomy
University of Pennsylvania

-----" A journey of a thousand miles must begin with a single step."

[Dieter S]

Craig's answer that the same GPIB board can control multiple instruments is correct, also the IEEE 488 specification limits the maximum number of devices to 14 on any given bus (or 15 loads, including the GPIB board itself). Craig is also correct that you may write to multiple instruments at the same time, but you may only read from one instrument at a time.

Fan, you may want to check out some helpful articles in the NI Developer Zone on GPIB communications. You can get to the GPIB content by going to http://zone.ni.com and then selecting the link for "Resource Library" in the left-hand navigation bar. Then click on the link for "GPIB". This will take you to the GPIB Resource Library, which has a lot of useful GPIB tutorials and examples.

Regards,
Mr. K
B

[Rick Nelson]

Don't GPIB communication programs require you to specify an address? I
think there should be 32 addresses (0 -> 31), and you assign your
hardware an address. Just assign each meter a different number (via
their own on-screen menus), and specify that in your GPIB calling
programs/VIs.

--
Rick

[Fan Zhang]

Thanks.

I also asked the technical representative of NI, they told me I can have 16
devices with one board.

The reason why I asked this question is after I plugged the cable for the
new device into the board, the instrument explorer can not see anything!
Even the multimeter disappeared. So I got confused...

Fan
Rick Nelson wrote in message
news:3A8C5B61.7A7238B3@csciences.com...
> Don't GPIB communication programs require you to specify an address? I
> think there should be 32 addresses (0 -> 31), and you assign your
> hardware an address. Just assign each meter a different number (via
> their own on-screen menus), and specify that in your GPIB calling
> programs/VIs.
>
> --
> Rick

[CraigGraham]

Fan Zhang wrote in message
news:96i5hq$bt8$1@netnews.upenn.edu...
> Thanks.
>
> I also asked the technical representative of NI, they told me I can have
16
> devices with one board.
>
> The reason why I asked this question is after I plugged the cable for the
> new device into the board, the instrument explorer can not see anything!
> Even the multimeter disappeared. So I got confused...

With only two devices there's not much scope for making a mistake in the
wiring.

Make sure a GPIB cable comes from the card to the first instrument, then
another cable piggybacks on the connection to the first instrument and goes
to the second. Make sure the cables are good- if they're off a shelf
somewhere there may be a bad con
nection, since they get flexed a lot where
the wire comes out of the connector.

It may be a problem with MAX. There's a simpler command line utility-
ibic.exe or somesuch- that's useful in such cases. It's much simpler than
MAX and there's less to go wrong. Since you should know the addresses of the
instruments you may find it useful to try sending commands directly to them-
"findlstn" takes a list of addresses and tells you what addresses have
devices listening on, which is always a good check.

You HAVE set all the addresses I assume? Each instrument will have some way
of setting the address. The addresses need to be different. Bear in mind the
GPIB card is also an instrument and has an address on the bus. Any conflicts
will stop things working.

Can you see the temperature controller if it's the only thing connected? If
the GPIB interface on it has died that could be killing the bus while it's
connected.

[Rick Nelson]

Actually, I've had trouble with this also. Installing a GPIB device is
hit-and-miss for me. I keep trying, and after about half an hour of
fiddling, it wil suddenly recognize it. Weird.

--
Rick