Gee-Whiz USB to GP-IB converter

[thijsbeckers]

OK: Talking to myself here...

Yeah, it sometimes looks like that, but there's a lot more people just viewing and absorbing the information than there are replies.

Rest assured your updates are highly appreciated!

[graxam]

Hi AndersG,
I have successfully made the GPIB I/f and with the latest software it works fine. The early version on the Elektor website is very unreliable I am afraid. With the latest version on board I would like to use the EZGPIB sofware. I have downloaded the version of 2012-12-17 (size is 1,845,760 bytes) from the website and tried your edit on the HEX file to make it ignore RTS. I cannot find the sequence you specify in my HEX editor. Can you let me know the location in the file ?

I echo the last post - we are all ears out here and are very appreciative of your design and implementation.

Best regards

Graham
M0HGZ

[graxam]

Hi AndersG,

I'm a bit stuck. I had hoped to use the Gee-Whiz as a controller with the PyVisa module and the Visa library.

I am new to this field but it does not seem to be possible to address different devices on the HPIBbus when the interface appears as a serial line. Although it is connected via a USB, GW appears as COM8 in my system and as such can only be addressed in Visa as "asrl8" whereas a true GPIB interface can be addressed as "GPIB::InstrumentAddr"

Is this the case ? Are there any plans to make the GW interface able to address the GPIB from Visa ? As per my previous post I cannot get EZGPIB to work either so I am stuck for the time being.

I think that I might be better addressing the GW dirctly via PySerial and not use libraries at all.

I would be interested in your thoughts.

Best regards

Graham

[Elektor Editor]

Everyone following this thread, please be advised that it is being continued at www.elektor-labs.com in terms of software updates and a follow-up project. Keyword: GPIB.
The author, Anders Gustafsson, is available there, please give him your support.

Jan

[andersg]

OK. First things first. The 2012-12-17 version of EZGPIB is the one I have used. Drop me an email at anders.gustafsson@pedago.fi and I will send you my hacked executable.

Best thing though would be if the author of EZGPIB would add a switch to his software to disable RTS detection. When I mailed him he promised to look into it, provided I sent him the interface, but I am not THAT keen

[andersg]

I am not familiar with PyVISA, but my interface will show up just like a prologix one, or prologix clone for that matter. As a com port. From a very cursory read of the PyVISA docs:

import visa
keithley = visa.instrument("GPIB::12")
print keithley.ask("*IDN?")

But I found this:

http://wanglib.readthedocs.org/en/latest/gpib.html

Try that and see if it works!

[andersg]

Yeah, it sometimes looks like that, but there's a lot more people just viewing and absorbing the information than there are replies.

Yes, I know. Lots of times, I do the same, ie just lurk. As for responding... I was 100% sure that I had subscribed to this, but apparently not.

[andersg]

@Graxam

The early version on the Elektor website is very unreliable I am afraid.

Well, yes and no. It worked perfectly or data-collection from my counter and DMM, pulling data into Excel for analysis.

The code had several issues that exhibited themselves when using other instruments though, but at that time, I had no access to any such instruments for testing. The real testing happened when others started building the adapter and I revised the code, based on that.

I also got several requests for Prologix emulation. Adding that was not trivial, but well worth it as it allows you to use most off-the-shelf software as it is. I used the KE5FX toolkit and EZGPIB as a testbed for that.

The problem with VISA seems to be that there is a default driver, not for Prologix per se, but for the FTDI USB adapter chip that the Prologix interface uses. My adapter, otoh, does not use that, but rather the Microchip built in one, saving a chip. In theory, they should be the same, but in reality there are snags because handhaking is done differently.

Issues like that will happen with all adapters that do not use the FTDI chip, so in that case, Google is your friend.

The next project:
http://www.elektor-labs.com/project/hpdisk-an-sd-based-disk-emulator-for-gpib-instruments-and-computers.13693.html

Is really a spinoff of this. It uses the same base GPIB code and the issues I see here will be ported back to the Gee-Whis code.

Meanwhile, the potential issues I have with the new project is the same as with this. It works perfectly with my HP1631D analyser, but Id be happy if anyone else could test with other instruments as well. Hence the SOS on the image

[Guest]

Will it work?
I came across this project during a search. What I'd like to do is dump screen data from an old HP4194A analyzer to a USB laser printer. I currently am using an old HP Thinkjet w/GPIB interface (works just fine), but am worried about the continued availability of ink cartridges, or what to do if the printer just ups and dies (it's been chugging along for 20+ years).

Anyway, all of the other interface products I've seen presuppose that there's a cumputer betwween the data source and printer - I want to avoid that. Is this project appopriate for a simple screen data dump to a printer?

[andersg]

Yes, the setup assumes there is a computer in the mix. You can then use any of the KE5FX utilities to grab a screendump, or my utility for the HP1631D available at http://www.dalton.ax/gpib, it has been tested with various analysers as well.

Most of the time, for me, getting the output as a file is far more convenient.

That being said, the hardware could possibly be adapted to serve as an USB host to drive an USB printer directly. It will take some programming though. I might look into it, but that will be after I finish my HPDisk project.