In the world of (expensive) lab test equipment the GPIB (general purpose interface bus) connection is hard to avoid if you want any kind of automation, but nobody likes wrangling with the bulky cables and compatibility issues when they can just use Ethernet instead. Here [Chris]’s Ethernet-GPIB adapter provides an easy solution, with both Power over Ethernet (PoE) and USB-C power options. Although commercial adapters already exist, these are rather pricey at ~$500.
Features of this adapter include a BOM total of <$50, with power provided either via PoE (802.3af) or USB-C (5V-only). The MCU is an ATmega4809 with the Ethernet side using a Wiznet W5500 SPI Ethernet controller. There is also a serial interface (provided by a CH340X USB-UART adapter), with the firmware based on the AR488 project.
The adapter supports both the VXI-11.2 and Prologix protocols, though not at the same time (due to ROM size limitations). All design documents are available via the GitHub repository, with the author also selling assembled adapters and providing support primarily via the EEVBlog forums.
Wow – this could not come more timely as I recently acquired a trusty old HP 53131A frequency counter in pristine condition (super bright VFD, clean, no smell, caps looking good so far). Looking around the Prologix adapters seemed like a valid option but their pricing felt way off for my hobbyist needs – so now I can spend my money on this project for GPIB, an aftermarket 3 GHz upgrade (option 030), an aftermarket OCXO upgrade (option 010) for standalone operations (both open hardware designs by circuitvalley.com to be found on AliExpress and eBay), and a GPSDO with TCXO to calibrate the then option 010 OCXO in the frequency counter.
The issue is that not all HPIB ports/equipment will behave as expected, and the software side is often a bit of a fools errand.
The older model Agilent 82357B USB-GPIB adapters are around $100, and will actually work on most platforms. I use this with the HP 3457A and HP 6625A setup to run through automated testing.
The BG7TBL 10MHz GPSDO can be good if you plan for the periodic GPS satellite updates (will take time to re-lock every few days), good weather, and avoid buying a broken clone. The BG7TBL FA2 frequency analyzers also work well for UHF, but only if you don’t need an actual edge counter.
Cheers =)
Yeah – the BG7TBL devices seem to be the go-to “prosumer” option as far as I can tell from my research so far. Can anyone tell me / us more about the background of BG7TBL? They are available on all major platforms as well.
For starters I got a cheap 60€ GPSDO which I definitely would like to compare to a BG7TBL (and some higher tier standards like Rubidium or Cesium). I have not made friends with some calibration lab guys yet – but that’s the next goal on my bucket list.
BTW: What are your thoughts on the BG7TBL versions? GPS, GLONASS, BAIDU, GALILEO etc.? Seems they can be (de-)activated via the serial port? Any experience regarding impact on the OCXO? Or Allan deviation / phase noise?
The EEVblog has a detailed list of current/legacy models, how the NEO-7M function with the internal OCXO, and which older models had firmware issues.
Anecdotally, the pps output has some jitter (better than some gps modules, but not great). Yet the 10MHz sign-wave for my SDR, counter, and scope is probably the most accurate reference I have on the bench. I was able to catch the slow drift of my equipment’s calibrated internal clocks with age.
Note too, I was able to replicate the box orientation-change clock-drift test after about 23 minutes to warm up, and get basic lock.
If I recall, the original project years back was based on a German Ham Hobby groups work, but they took down their own site pages after they were commercially cloned with zero citation. It is bitter-sweet recommending the popular GPSDO clones, as the original team that created the design never saw general community support (will post the archive.org link if I remember their names at some point.)
Cheers =)
73
VE7NTP
Thanks for the shoutout! If any one wants to order one and is either on too low post count on eevblog or do not want to register, I created this quick and dirty online form so you have an alternative.
Go to: kofotronic.com
A vast amount of truly excellent instrumentation is sitting on shelves or in storage or in surplus stores due to HPIB. This is a pretty neat solution!
One would guess it can also be a Commodore floppy controller, and maybe at a more usable speed.
Oh man, I wish this had been out a few years ago. I just sold my beloved HP54602B, one of the reasons being that I couldn’t easily automate it. Ah, the time wasted with ancient NI-GPIB-USB drivers…
I use the Prologix ones, recently tried buying an alleged “new old stock” one to save a few bucks but it failed to operate properly. Contacted Prologix support and though they were helpful the root cause was that I had purchased a counterfeit item. I purchased a genuine adapter from Prologix, and set about trying to get a refund for the counterfeit item. To my surprise the seller accepted my complaint and refunded me in full immediately, thought he did not admit anything related to counterfeit he also sent another item as a replacement.
This arrived some months later and as I already had the genuine item in service I wasn’t in a hurry to test it out. However to my continued surprise this second ‘counterfeit’ item does in fact work correctly. So I got a “buy one get the second half price” sort of deal in the end. I don’t recommend you try it the way I did.
PoE would be a nice to have
Curious about conterfeit prologix, have never heard of it before, do you by any chance have a photo of the innards of the fake one? Curious to see what they used.