Time out problem in reading from HP instruments with NI GPIB card.

[phy]

Hello,

I have a problem when reading results from the HP instrument with NI GPIB card over GPIB interface. In NI spy program it seems that my program sends i.e. ID? query ok, but doesn't get any result leading to timeout. The HP instruments changes its state to TALK mode. It can be seen on its front display.

I made a question to HP and got the following answer:

"The 3784A requires a CR followed by LF after each command sent. All the commands from the national cards are ended with UNTALK aand UNLISTEN commands. The National Instrument GPIB card can loose the last character (ie LF). This
happens because the ATN line on the bus is set true too soon before the the UNTALK command
is sent thus loosing the LF. There is no solution to this problem apart from using A HPITG2 card instead of the NI card."

The HP's instrument is so old that there is not available drivers (or I haven't found) for VISA commands which could be used in LabWindows for HP's GPIB card. I'm also using in same GPIB bus Philips and R&S instruments which are working fine (with similar commands) with the GPIB commands.

So, is there any solutions to go round of this ? I.e. newer driver for GPIB card. Or is there low level programming possibility to detect the incoming data from HP ?

I'm using LabWindows/CVI 4.0.1 with NI's PCMCIA GPIB card with driver version 1.30.0041 dated May 4 1998.

[RayFarmer]

Hi,


It should be possible to setup the EOS character or even switch it off so that you can match the requirements of the hp3784A. Look at the ibconfig function.

Ray Farmer

[Ryan_M]

If you don't have readdressing enabled then the driver should not UNT/UNL the bus after every communication.

Also, a thing to note is that the driver does not automatically append the EOS character to any strings you are writting. The EOS character will be used on all reads but it is the users responsibility to add that "\r\n" to the end of any communication to the instrument.

[TomB]

Did you get your problem solved? I am having a similar problem, different instrument, different card and software, but buss hangups that cannot be cleared without restarting my application. I would be interested in hearing about what you did to resolved your problem.

[CPeterS]

While the answer is in the original post, it is even more obvious here:

http://forums.ni.com/ni/board/message?board.id=140&message.id=16929&query.id=11127915#M16929

Best

Peter

PS: it is an ancient thread, but I faced the issue yesterday...