The board class has it, the syntax is board. If you have problems when using more than one port at the same time then it might have something to do with the virtual port driver and threading, read “query sequence and lock levels” in the last section. This is most efficiently solved using the “poll” feature of GPIB: Looks like you’re from the United States. ResponseAsString’ threw an exception of type ‘System.

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I inherited a batch of GPIB controllers from vlsa division. I am able to connect to the gpib but the sendasync command is failing. Device-dependent conditions, such as the presence of available data or an error condition, determine this value. You may choose two devices eg.

PyVISA: Control your instruments with Python — PyVISA dev0 documentation

They provide a complete independent way to verify the communication with your instrument. Running line by line the only exception I can find is: Computer buses Electronic test equipment. I’ve been choosing to use the GPIB because to a new labview programmer, they seem simpler to use, or at least more intuitive in the beginning, but if the VISA functions really are better, I need to learn to use them.

Each device has its own queue and runs its own dedicated thread processing queries from the queue.

If there is a problem, you no longer see your device. With this test panel, you can set properties for your instrument communication as well as read and write to the instrument. Most devices comply to You can find it in: Using your computer, you can take advantage of this powerful development and debugging tool to interactively communicate read, write, serial poll, and so on with your GPIB instruments.


Instrument control

If you have two or more instruments on the bus, you can disconnect all instruments except one to determine its address. Repeat this process to confirm communication with all of your connected instruments.

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The basic functions and concepts described above may seem simple; however, they can be invaluable in troubleshooting and getting your GPIB system up and running. Wow, lot of meat here and worth the read. A lot of work went into this and it is appreciated. The amount of research and true hacking you have done to write this article is amazing. Instruments must visq powered on and connected to the GPIB controller vosa be recognized.

VISA Write – writes a command vissa to an instrument. Click here to see To view all translated materials including this page, select Country from the country navigator on the bottom of this page. NullReferenceException’ I am not sure if that is due to the fact that SendAsync does not read anything back so the response is always null or if it actually is an error.

The situation got even more complex as LAN interface has become the standard in the computer industry. Then the method ” WaitAsync ” can be used for synchronization between the asynchronous command queue and the main thread: In the example above it signals that a device is not connected and that the query will be repeated, once it is viss the message will disappear.


Instruments can be programmed by sending and receiving text based SCPI commands or by using an instrument driver.

Note that the standard GPIB libraries also provide a sort of asynchronous operations, however somewhat limited, for example it is said in the NI reference manual:.

The SendAsync method returns 0 which means it is working ok but when the method completes and the command is actually sent, it times out. If you want detailed information about communicating with an instrument connected to the serial port, refer to Serial Port Overview. As the software has been made sufficiently general to adapt it to various Gpib libraries it could eventually also be adapted to other interfaces such as the Visa library and the serial port.

GPIB-to-VISA Migration – GPIB-to-VISA Migration – National Instruments

The latter is used internally to access forms displaying the device list and error messages and does not need to be imported in the application. The examples also use specific instrument addresses, SCPI commands, and so on. There’s an identical instrument in the lab but it has a USB interface.