Inexpensive GPIB

Not that long ago I was looking for an inexpensive GPIB controller I could interface via USB and would allow me to control test equipment with. I planned to control the equipment with my own software so I was not looking for anything that had to work with existing NI or Agilent GUIs. I needed something that had its own (preferably easy to use) API.

GPIB is not something widely popular unless you are into electronic test equipment. As such its market is not mainstream and is dominated by a few major players that usually charge accordingly. Through my research I found popular items from National Instruments, Agilent, Prologix, etc. They were probably great tools on their own but the cheapest one was $150. I could also roll my own with an Arduino or AVR, but I thought there had to be something out there. As it turns out there was. Some group by the name of LQ Electronics had a couple of options which are probably AVR based with some driver tool included (this is similar to the Prologix approach). I found them on Amazon, and for $44 you can get the "UGPlus USB to GPIB Controller" which I think is an excellent value. How could you beat that. I decided to give it a try, worst that could happen is that it didn't work and I have to return it to Amazon (win-win).

The controller came in within a few days of ordering, which was great. It includes a very simple (I would say crude) GUI which is ok. I would only recommend using that GUI to quickly checkout the operation of the device and test it out. I was able to build a custom program using the std library (dll) included and the instructions and examples provided. Within a few hours I was communicating with an old Fluke DMM.
As far as using the functions within the DLL, the Find instruction I don't think works all that great (but I have no need for it). The Write function worked very well. The Read function worked about half the time, but it I followed the Write function with the Read function it seemed to always work. Turns out this was more of a function of the device I was controlling rather than a function of the controller itself.

I've tried this controller with an old Fuke DMM, an Agilent 443x Signal Generators, an Aeroflex NAV2000 signal generator, Agilent power supplies, and Sorensen power supplies. It works great with the newer equipment (Agilent, NAV2000, Sorensen); read, write, and query functions. It works ok with the Fluke DMM, which I had to work around with timing on the read instructions. I now believe the difference with the Fluke DMM is that while the newer equipment is fully compliant to the IEEE488.2 interface, the Fluke DMM is only partially compliant with the IEEE488 interface. After the initial configuration and troubleshooting I had it driving three pieces of equipment without any issues. I highly recommend this controller for its value and the ease of programming.

A word of caution follows. To use the device with your own custom program you still need to install the provided program as it installs drivers and DLLs that you will need. I contacted customer service to ask about this and they promptly responded that doing this was required in any PC you plan to use the controller. Not a bad thing, just something to keep in mind.