Instrument Control (GPIB, Serial, VISA, IVI)

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NI MAX not detecting instrument properly



I have an HP 5350B frequency counter and I have been working with it for automating some measurements. It has an HPIB port on the rear of the cabinet. This is the only instrument connected to the computer at this moment. When I go to NI measurement and automation explorer and scan for instruments I get multiple instruments instead of one (as shown in the screenshot attached). Also none of these detected instruments seem to understand the '*idn?' command as it gives an error while reading from the instrument.


What can I do to establish communication with this instrument?


I would really appreciate comments on this.


Thank You,



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Message 1 of 7
Its not supposed to respond to the *IDN? query. Use the correct command as listed in the manual. MAX is listing 1 instrument with multiple secondary addresses. I'm not sure why. The instrument is very old and its certainly possible the GPIB interface is bad. Try swapping cables and a different instrument.
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Message 2 of 7

Thanks for replying. Yes, the instrument is old and dose not respond to an *IDN? query. So I tried to communicate with one of the 31 instruments with a secondary address shown in the above snapshot using the 'ID?' query command(As given in the operating manual and is equivalent to the *IDN? query). The instrument does respond to this code by provding the model number of the instrument but also gives timeout errors just below the results in NI MAX. I tried interchanging the cables but it dosen't help. I tried using a different frequency counter with the same cables and that instrument seems to work properly.

I would really appreciate help in this regard.





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Message 3 of 7
I have not read the manual but its possible that you get a timeout because it is not asserting EOI. Some 488.1 instruments did not. They used a CR or LF or some combination. Sometimes with an EOI as well. You can change the termination in MAX. With GPIB functions, you have an optional setting on the read and write. I think you can also set it for VISA but I'm not on a computer to confirm that.
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Message 4 of 7

Hi Vivek,

I have same problem with my HP5350B and HP5351B.

Did you resolve it?


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Message 5 of 7

Hello Kimosabe,


This thread is fairly old, so I would suggest creating a new thread. This would incease traffic and visability to your issue. 



Karen M
Applications Engineer
National Instruments
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Message 6 of 7

I'm having the same problem, I think it could be that the HP 5350 is in the talker mode. The operator's manual under HPIB talks about it. My question now is it possible to configure NI MAX for instruments in the talker mode.


GPIB Devices can be Talkers, Listeners, and/or Controllers. A Talker sends data messages to one or more Listeners, which receive the data. The Controller manages the flow of information on the GPIB by sending commands to all devices. A digital voltmeter, for example, is a Talker and is also a Listener.

The GPIB is like an ordinary computer bus, except that a computer has its circuit cards interconnected via a backplane - the GPIB has stand-alone devices interconnected by standard cables.

The role of the GPIB Controller is comparable to the role of a computer CPU, but a better analogy is to compare the Controller to the switching center of a city telephone system.

The switching center (Controller) monitors the communications network (GPIB). When the center (Controller) notices that a party (device) wants to make a call (send a data message), it connects the caller (Talker) to the receiver (Listener).

The Controller usually addresses (or enables) a Talker and a Listener before the Talker can send its message to the Listener. After the message is transmitted, the Controller may address other Talkers and Listeners.

Some GPIB configurations do not require a Controller. For example, a device that is always a Talker, called a talk-only device, is connected to one or more listen-only devices.

A Controller is necessary when the active or addressed Talker or Listener must be changed. The Controller function is usually handled by a computer.

A computer with the appropriate hardware and software could perform the roles of Talker/Listener and Controller.

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Message 7 of 7