Third-party USB-GPIB controllers?

[DaveCC]

Does LabVIEW software require N.I. brand controllers? Will other USB-GPIB controllers work with LabVIEW? 

I'm hoping that the controller (specifically the USB ones) are transparent to the software and don't need to be N.I. brand. 

For example:

<http://www.sparkfun.com/search/results?term=gpib&what=products>

Any help answering this question would be greatly appreciated. 

Thanks,

Dave

[Dennis_Knutson]

That's a Prologix and it's design is not a true USB-GPIB. It is more a serial-GPIB and it is NOT transparent to existing instrument drivers. Just do a search for 'Prologix'. Other third-party controllers are useable as long as they come with a VISA driver.

[DaveCC]

Thanks for your reply. 

Looking at Proligix's web site, I see this on their FAQ web page for USB-GPIB controllers:

"

Q: Will my NI LabVIEW, or Agilent VEE, programs work unmodified with Prologix GPIB-USB controller?

A: Probably not. Prologix GPIB-USB controller provides a virtual serial interface to communicate with instruments, while handling all GPIB protocol details for you. Programs that expect a GPIB interface (such as NI 488.2 interface) must be modified to use the serial interface to work with Prologix GPIB-USB controller.

"

So, it looks like the Prologix controller is not out-of-the-box compatible with LabVIEW. How will LabVIEW need to be modified to work with Prologix's controllers?

Thanks,

Dave

[Dennis_Knutson]

As it says, you need to change to a serial interface. In some cases it can be done in a single location (i.e. the initialize function) where you might simply need to change the VISA settings to append a termination character. In the case where the driver uses the LabVIEW low level GPIB functions, you will have to replace each and every one with VISA serial functions.

How much time this will take will depend on your skill level with LabVIEW. For me, it might take a couple of hours to a day per driver. Which brings up the second point of how much is your time worth. For me, spending much more than a couple of hours will more than offset the couple of hundred dollar difference between the Prologix and a GPIB controller from NI. In just the last month, I have worked with 5 different GPIB instruments and there will be a couple of diierent ones in the next month. It would be silly of me to waste my time doing all of the modifications and debug required. If you are a student and going to be doing work with a single instrument for a single application, it might make sense.

p.s. The serial interface of the Prologix is also much slower than a trueUSB-GPIB. About half the speed.

[DaveCC]

Thank you for your reply.

I don't understand why the Prologix controller isn't a "true" USB-GPIB controller. It's got USB; it's got GPIB; it controls. 😉 On paper it looks just like the National Instruments'. 

What am I missing? 

Thanks,

Dave

[Dennis_Knutson]

It doesn't look anything like the NI controller (or Agilent, Keithley, whatever) on my paper. If you were familiar with IEEE.488 specs you would see the differences. USB can be used to emulate many things. The prologix is a serial interface to windows - not GPIB. You use an RS-232 terminal program to talk to it. This is not standard. You have to append termination characters (i.e. CR/LF) to send commands. This is not standard. It does not support the minimum communication rate of 1MB/s. Read the manual and compare it to the IEEE specs and see if it implements each and every interface management line, control sequences, protocols, etc.