NI-Visa advantages

[-mbda-]

Hi - I am a newbie in NI-VISA and I am starting this Visa project in .NET framework that will handle certain type of instruments and its various models, if this is stupid question please bear with me. First, what are alternative paths that I can take aside from NI-VISA? (I know some of you might say that this is NI forum but I am hoping to get an honest answers) What are the advantages of NI-VISA over its alternative? (Aside from the advantages that are listed in the documentation) What are the disadvantages of NI-VISA?

Another information that I gathered is that per model of each instrument the commands change? Is this true for all instruments?

If someone can give me a good reading material, that will be AWESOME!

Thanks in advance

Message Edited by mbd on 08-16-2007 04:01 PM

[Brian F.]

Hello. 

Thank you for posting to the NI Discussion Forums.

The overall advantages of VISA are explained well at the following website:

NI-VISA Overview
http://zone.ni.com/devzone/cda/tut/p/id/3702

You can think of NI-VISA as a layer of abstraction that is built on top of the NI-488.2 driver.  So, the really cool thing that VISA does is that VISA makes it easier to program the same functionality that can be achieved using our 488.2 driver.  This is not uncommon as Agilent also has a VISA driver, called convienently enough, Agilent VISA. 

VISA is a very stable driver since the technology that VISA supports has been around for a long time.  So, VISA has been optimized and constantly improved over the years, bringing us to a point where our users can be confident that VISA will work for them. 

In terms of the disadvantages of VISA, I honestly cannot think of any.  I think this would be proven if you give NI-VISA a try!   

In terms of your question about the commands changing from instrument to instrument, most of the industry has standardized across the SCPI (Standard Commands for Programmable Instrumentation) standard.  As the name implies, all instruments that are SCPI compliant can be controlled and programmed by the exact same command set making it easy to communicate with any instrument.  Some instruments do not comply with SCPI and these instruments will have a different command set outlined in the user's manual for that particular instruments. 

I know that this may not be the response that you necessarily want which would be a detailing of other options available to you.  The only other option that I can think of is using specific drivers provided by the company that provided the hardware.  However, if you have say 3 different instruments, using 3 different drivers from the manufacturers, the learning curve could be significantly increased since you have to learn all 3 drivers and have them work together.  Using NI-VISA will allow you to focus on one driver to communicate with the same 3 instruments and should save you a lot of time!

I encourage other people that read this forum to go ahead and give their 2 cents as well! 

Good luck!

Brian F
Applications Engineer
National Instruments 

[-mbda-]

Thanks Brian, your reply is really helpful!

Basically, we are decided to use NI-Visa but I just wanted to know what other alternatives we can use aside from NI-VISA? I just wanted to make sure that I am considering all paths.

excerpt:

"I know that this may not be the response that you necessarily want which would be a detailing of other options available to you.  The only other option that I can think of is using specific drivers provided by the company that provided the hardware.  However, if you have say 3 different instruments, using 3 different drivers from the manufacturers, the learning curve could be significantly increased since you have to learn all 3 drivers and have them work together.  Using NI-VISA will allow you to focus on one driver to communicate with the same 3 instruments and should save you a lot of time! "

Is this one of the alternatives that you are saying?

Based on your example, is the 3 instruments assumed as SCPI standards and that is why we can use NI-VISA for these? Is that correct?

[Brian F.]

Hello. 

You are correct in stating that one of the alternatives was using all drivers native to the actual hardware.  However, this would not be optimal because it forces you to potentially use n drivers, where n is the number of unique instruments in your setup.  The n drivers will take time to learn and are not guaranteed to work with each other well.  However, if you go with NI-VISA, you have one driver for all instruments. 

Having SCPI compliant devices is very helpful when programming because SCPI compliant devices have the same command set.  However, NI-VISA does not require that you have SCPI devices.  NI-VISA will also work with non-SCPI devices.  It will just require that different commands be used to communicate with the non-SCPI instrument. 

Brian F
Applications Engineer
National Instruments