IEEE-488 (aka GPIB or HPIB) - Page 1
Forum section: electronics / testgear

author: MrAureliusR
author_rank: Unknown
timestamp: August 17, 2013, 04:22:21 am
content: So I'm wondering if anyone knows much about this interface. There's quite a bit of information on it's Wikipedia page, but I've been unable to find much about actually using it to connect to a computer. I recently got this cool double serial/single parallel port PCI card for my main PC beside my bench. I'm going to have some equipment that has an IEEE-488 port on the back and nothing else for communication.I did a quick Google search and it seems the interfaces that convert from GPIB to USB or PCI are typically $500 and up ... but that's not really what I want. I just want to convert from IEEE-488 to IEEE-1284 (standard parallel port) because then all the conversions (I'm guessing) can be done in software... The pinouts aren't hard to work out, I'm just trying to figure out the best way to approach this problem. Should I just create a small adapter that just re-arranges the pins? GPIB has 24 pins and the standard parallel port has 25 (DB-25). Of course, I didn't really look into converting to RS-232 but that's probably crazy expensive too..Aha, I just answered my own question. I'll post this anyway in case someone else runs into the same problem. I found a great PDF from the Giant Meter Radio Telescope, Tata Institute of Fundamental Research. Apparently they had a bunch of instruments that ran with GPIB that they needed to control from parallel ports and they decided to share their solution with the internet!http://ncralib1.ncra.tifr.res.in:8080/jspui/bitstream/2301/344/1/interface%20between.pdfI've also uploaded the PDF in case that link goes dead.This guy also created a GPIB to USB adapter himself:

author: c4757p
author_rank: Super Contributor
timestamp: August 17, 2013, 04:25:17 am
content: Parallel port? What's that?I may have to build a USB-parallel adapter to go with my parallel-GPIB adapter...

author: MarkL
author_rank: Unknown
timestamp: August 17, 2013, 08:47:04 pm
content: There's no need to spend $500+ on a GPIB interface.There's plenty of choices on ebay for GPIB PCI cards for less than US$75, like the HP/Agilent 82350 or the NI PCI-GPIB (TNT4882 chipset). You can get an even cheaper card if your machine happens to have a retro ISA slot. Unless a side goal is to learn about GPIB, I would just get the card and get on with the data gathering.RS232 to GPIB also exists, such as the Iotech Micro488A. I've used these and the out-of-band GPIB signalling is difficult to manage over RS232, especially if you're trying to talk to older (non-SCPI) equipment. Unless you're forced to use serial, like over a modem (what's that?), I wouldn't go this route.Also be aware that good quality GPIB cables are not cheap, like the HP/Agilent 10833 series. But these are also in abundance on the 'bay.

author: Unknown
author_rank: Unknown
timestamp: August 17, 2013, 09:10:16 pm
content: One thing that is important to decide is whether you will use software from companies like NI and Agilent, or whether you'll write your own software. In the former case you want VISA and GPIB32 support, and are basically limited to products from NI or Agilent or the various clones. In the latter case it doesn't really matter, and for example thePrologixproducts are also good options.

author: kevinpt
author_rank: Contributor
timestamp: August 17, 2013, 09:20:35 pm
content: Now is a great time to pick up PCI GPIB cards cheap on eBay as the industry has begun its shift to LXI and other industrial control interfaces. Lots of salvage shops are pulling these cards out of unwanted test equipment and selling them for a good price. They are in far less demand than the USB and ethernet converters. You would be much better served going that route than trying to find some parallel port based-converter. I've never seen one but GPIB to serial is not uncommon.Be aware that the GPIB interface has special bus level commands that have to be emulated when it is converted to a protocol with a single "command stream" as with asynchronous serial or a parallel port. This is done with some form of escape code mechanism and it can vary from converter to converter as there is no standard for that sort of behavior. Many older instruments with GPIB and serial ports use the same command set over their serial port, again each with their own schemes for emulating the GPIB bus commands.

author: Unknown
author_rank: Unknown
timestamp: August 17, 2013, 10:53:11 pm
content: The only issue is that PCI is starting to disappear from desktops and obviously doesn't work on laptops. Not a big deal if you have a dedicated computer for the lab, but this might be a consideration if you have limited space. USB is not going to disappear anytime soon from either laptops, desktops or even embedded systems (eg. Raspberry Pi).

author: JackOfVA
author_rank: Unknown
timestamp: August 17, 2013, 11:41:09 pm
content: I like the Prologix IEEE-488 adapters and have three or four here. It's available in two versions. One is USB interface that emulates a standard RS-232 interface and the other is Ethernet.USB version is around $150 and the Ethernet model is $200. More info athttp://prologix.biz/Let me also relate a story about Prologix's customer service ... One of my adapters was an old Model 4.2 - probably three or four years old - and a few months ago, I tripped over the USB cable. Completely my fault, and the USB connector was ripped off the adapter's PCB. I removed the damaged connector and tried to find a mechanically matching connector, but while I could come close, I couldn't quite match the footprint and mounting holes. I sent Prologix's owner an E-mail, explaining that I had tripped over the USB cable and damaged the connector and asked for the correct part number so I could buy a replacement or if he could supply a replacement. Received a reply E-mail later that day informing me that a replacement would be on its way to me, without charge.Two days later, a large box arrived from Prologix, and when I opened it up, inside was not a replacement USB connector but rather a new version 6.0 adapter. Needless to say, that degree of customer service is rare in the extreme these days.Another story about Prologix ... my first adapter was a model 3.0 and I found that it had handshake problems with one particular piece of HP gear, a gain/phase analyzer made by HP's Japanese division. After an exchange of E-mails with the owner of Prologix, and some data dumps, he patched the code and sent the update within a couple days. Problem fixed.

author: MrAureliusR
author_rank: Unknown
timestamp: August 18, 2013, 09:50:36 am
content: Wow, that's incredible service! Ill definitely keep them in mind! And good tip about the GPIB PCI cards. All my motherboards have at least 1 PCI slot and my lab computer has 2. It's definitely starting to get full but the serial/parallel card's parallel port is on a separate mount and is removable if need be to free up that slot.Oh and I'll be using a mixture of HP/Agilent gear and Fluke /Phillips. I'm guessing they use completely different protocols? It sounds like it from your post.Typed using Hacker's Keyboard for Android

author: Unknown
author_rank: Unknown
timestamp: August 18, 2013, 01:07:32 pm
content: All (except the really ancient) will conform to IEEE 488.1 (or a precursor of that) wire-level spec. So there should be no problem connecting them all to the same bus as long as you assign them unique addresses. In theory GPIB supports up to 14 instruments on the same bus. This should work fine with real NI hardware, but I think there have been some reports of the Prologix hardware being too wimpy to drive a long GPIB chain. The slowest instrument will determine the speed, but you're not likely to be doing high throughput data (GPIB supports up to a few MB/s) with a Prologix adapter. And throughput is irrelevant for most T&M applications unless you're doing real-time analysis, have huge data files or have a high-throughput automated test setup.The higher level protocol (eg. IEEE 488.2 or SCPI) will likely be different: equipment designed from the late eighties onward will likely support SCPI, which specifies a common grammar and somewhat common command set (the :VOLT:DC:RANG 10 type commands). Earlier instruments will usually use a more basic command set that's closely mapped to the front panel. For example R0 might be the leftmost range button, and you get strings like F3R4C3= (third function, fourth range, third filter setting). So even an HP 3456A (pre-IEEE488.2) and HP 34401A (SCPI) will use completely different protocols, although they can sometimes emulate older instruments to some degree.In most cases there will be at least minor differences between instruments, which is why you would generally implement an instrument driver per instrument. The protocols are generally described in the manual (programmers or users), although some instruments can be quite fiddly in what they accept (I'm looking at you, Keithley!).

author: G0HZU
author_rank: Super Contributor
timestamp: August 18, 2013, 01:50:59 pm
content: I'd recommend going down the USB to GPIB adaptor route because it is so versatile.For data gathering via GPIB I use a small netbook running Win7 starter and an 82357 adaptor. I chose the netbook because it was tiny and had a slow processor but had a big battery option so it runs for ages on one charge and wakes up in a few seconds even if left unused for a week or so.So with the netbook and the USB/GPIB adaptor I can plug into any test gear I have here regardless of where it is in the house and also I can use it away from the house.The netbook happily runs the Agilent IO libraries and MS VB6 so I can write/edit my own SW and the whole setup is neat and very portable. i.e. no trailing wires anywhere. Just the little netbook and the GPIB adaptor cable to pick up and carry.