Will it be any different if I call GPIB function instead of VISA to write to the device?

[dragondriver]

Hi all,

  I am still using LV7. I have a function generator using GPIB interface. In the labview code, I use VISA write to send commands to the function generator. But I am reading some related documents about GPIB in labview. I wonder what's the advantage of using VISA instead of GPIB for communication, also the interface is actually GPIB so what's VISA really doing in this case? Thanks.

[Dennis_Knutson]

VISA is portable. GPIB is not. Use the GPIB functions and you are tied to NI GPIB hardware. Use the GPIB functions and you cannot use the same code if you get the same instrument with a USB, Ethernet, or serial connection. Note that instruments with these connections are a lot cheaper to use.

The VISA api abstracts the actual hardware interface which makes the portability possible. Unless you are using some very low level and seldom used GPIB functions, there is simply no reason not to use VISA. Every instrument driver from NI, Tek, Agilent, and every other major instrument vendor is written with VISA. I started using VISA when it was first released and in all those years, I think I used a GPIB function once.

[moderator1983 · Accepted solution]

VISA by itself does not provide instrumentation programming capability. VISA is a high-level API that calls into lower level drivers. The hierarchy of NI-VISA is shown in the figure below:

Advantages of VISA:

1. One of VISA’s advantages is that it uses many of the same operations to communicate with instruments regardless of the interface type.

2. Another advantage of VISA is that it is an object-oriented language which will easily adapt to new instrumentation interfaces as they are developed in the future.

Reference:

http://www.ni.com/support/visa/vintro.pdf

[dragondriver]

Thanks all, it is very clear explanation and it clear many of my doubts while reading the code developed by someone else. Thanks