Prologix GPIB-USB Controller

[Rhythmtech]

I bought one of these for troubleshooting many of the older pieces of equipment at work.  At first I was somewhat reluctant because the closest similar product from National Instruments was ~$500

So far I have had no issues using it to communicate with an HP 34401A and a programmable variable frequency power supply.  I've only used it via the virtual com port, but it also has the ability to be used without dealing with com ports via the FTDI dll. 

Inside is a Atmel ATMEGA164P, a FTDI FT245RL, and a couple discrete components. No software, not even the driver is included, so support through the manufacturer is on the lean side but that was to be expected. The Ke5FX GPIB toolkit works with it though, so you don't have to start completely from scratch to get it up and going. There are several code examples to give you a good idea of how to get it working from within your application.  If you wanna look at the code and don't have a development suite, I've found Sharpdevelop to be a great free development environment for C# or VB .net.  Of course for C code all you need is a text editor at a minimum.

Overall I would say so far I am happy with it, it does what I bought it to do, and I didn't have to go too high in the chain of command to get it since it was cheap. 

[desolatordan]

Good to know. Where did you find the drivers for it?

[Rhythmtech]

Their website has a link to FTDI's drivers on FTDI's site, so you aren't completely lost. I actually had the driver installed already from using a RS485 cable from FTDI, which is the best/cheapest way to get an RS485 serial port on your PC in my opinion. If you've ever installed the Arduino FTDI driver you wouldn't have to do anything when you plug the GPIB controller in.

[Rhythmtech]

[allanw]

I don't get why there aren't any similar GPIB to USB converters that are much cheaper. The hardware can't cost more than $20 at most.

[alm]

There's a cheap one from Australia, but I believe it really sucks: it supports only two instruments or so, and offers no support to add other devices yourself. I assume there's a fair amount of research and tweaking in getting a GPIB adapter to work with all equipment, but can't imagine the per-unit cost to be much more than $20 or so either.

[Rhythmtech]

There's a cheap one from Australia, but I believe it really sucks: it supports only two instruments or so, and offers no support to add other devices yourself. I assume there's a fair amount of research and tweaking in getting a GPIB adapter to work with all equipment, but can't imagine the per-unit cost to be much more than $20 or so either.

GPIB is a communication standard and it's fairly old, how would only two instruments be supported?, that's really odd. Some of the newer (relatively) 488.2 commands are not supported by older instruments, but usually as long as you can send a command you should be able to get some functionality.  In some applications you may only need to send commands, like setting a power supply. If you are doing DAQ via GPIB then you would need to go both ways to set the instrument settings and record the data returned. 

Seems like an Arduino library would be cool to build up for GPIB. That is basically what the Prologix box is FTDI + Atmel mcu

[alm]

Because there's no API or documented protocol to use the interface, GPIB is not like a basic UART with just a stream of bits, but has all kinds of out-of-band commands like listen, address and SRQ (interrupt). The Prologix device converts it to a standard serial interface with ASCII commands, or a more advanced interface using included libraries. This device is only supported by the included software, and no documentation is provided how to program it (either API or how to write a driver). It might be possible to reverse-engineer it, but I'm not sure if it even provides a full GPIB implementation or just the bare minimum required for these instruments. I've heard various reports of people that bought it and consider the money wasted, and bought something else instead.

Note that an issue with the Prologix devices is that they're not compatible with standard interfaces like NI-488.2, so you won't be able to use any software written for 'real' GPIB interfaces like those by NI and Agilent. I think there's a compatibility layer for the USB version, but it looked stale and abandoned last time I checked. It's is properly documented to write your own software, and some hobbyist software supports it.

Re Arduino: one issue is that GPIB is a fairly fast bus (1.8MB/s, and I think the high-speed version is faster), not sure if the Arduino was designed for that.

[NiHaoMike]

What about design a little box that contains a small FPGA along with GPIB and USB PHYs? Have it start in firmware loading mode for easy firmware updates, which would be taken care of in the kernel module.

[alm]

That should work. The problems are probably being compatible with all the equipment out there and software support. The Prologix people have had to release fixes to get it to work with various pieces of equipment (after probably testing with lots of equipment during development), which suggests to me that either the GPIB standard isn't very well documented or there are lots of slightly different implementations in the world. The other is software compatibility. I'd probably either try to be API compatible with the NI stuff (probably hard since there's no actively maintained implementation for the Prologix GPIB adapters), or try to be compatible with Prologix to at least support some software. If you only want to do it for your own software, you can ignore all this.

[Rhythmtech]

Because there's no API or documented protocol to use the interface, GPIB is not like a basic UART with just a stream of bits, but has all kinds of out-of-band commands like listen, address and SRQ (interrupt). The Prologix device converts it to a standard serial interface with ASCII commands, or a more advanced interface using included libraries. This device is only supported by the included software, and no documentation is provided how to program it (either API or how to write a driver). It might be possible to reverse-engineer it, but I'm not sure if it even provides a full GPIB implementation or just the bare minimum required for these instruments. I've heard various reports of people that bought it and consider the money wasted, and bought something else instead.

Note that an issue with the Prologix devices is that they're not compatible with standard interfaces like NI-488.2, so you won't be able to use any software written for 'real' GPIB interfaces like those by NI and Agilent. I think there's a compatibility layer for the USB version, but it looked stale and abandoned last time I checked. It's is properly documented to write your own software, and some hobbyist software supports it.

Re Arduino: one issue is that GPIB is a fairly fast bus (1.8MB/s, and I think the high-speed version is faster), not sure if the Arduino was designed for that.

The slowest device you are using with GPIB determines the speed. There are all sorts of old slow equipment that I am sure is not using the older 1Mb/s or newer up to 8 Mb/s .  So I think it is possible to use an Arduino, just probably not at full bandwidth.

The prologix device is more like the NI serial to GPIB adapter in its functionality since you are not installing a GPIB device into the computer but using a com port instead. I have been able to use the prologix adapter with devices that use SCPI (HP 34401A) and a proprietary Elgar power supply language from 20+ years ago.  If you are writing your own software this not too bad, if you are expecting it to work with an NI or other front end, yeah not gonna happen ever. So it depends on what your needs are I suppose. If you are like me sending *IDN? while trying to troubleshoot GPIB communications on different setups of differing ages from different designers, sometimes it's nice to go real simple and see what does work, which is why I bought this one.   

[vizer]

Anybody know how the following unit from BEIMING Technologies compares with the Prologix GPIB-USB Controller?

ebay Item number: 170576114554
Low cost GPIB-USB interface, Agilent 82357B compatible
buy-it-now: USD 139.99 + 20.00 S&H

BEIMING Technologies
http://www.bmjd.biz/index_eng.html

[Mechatrommer]

I don't get why there aren't any similar GPIB to USB converters that are much cheaper. The hardware can't cost more than $20 at most.

from the circuit picture, i can see the most expensive part in the device is the "software".

[Fraser]

I saw the BEIMING Technologies product on ebay the other day and it looks a very interesting product but there are some caveats.

The BEIMING Technologies GPIB controller is apparently the same functionality as the Agilent USB-GPIB units and will even accept the Agilent firmware updates ! This would indicate to me that we are probably looking at a cloned Agilent product .... IPR ?

The problem I have with the BEIMING Technologies product is that it uses the Agilent and not the NI drivers. My requirement is for a USB to GPIB converter that works with a piece of software that expects to find an NI GPIB interface and drivers. I already have an ICS USB488 USB-GPIB adapter and that works because it emulates the NI product and is compatible with the drivers etc. It does have some compatibility issues though so is not really a 100% emulation :-(

If any one knows how well an Agilent USB-GPIB controller interacts with programs designed to work with a NI controller, I would be interested to hear from them.

From my understanding, the Prologix is/was the best value for money external GPIB controller that you could buy new. The product is not, however, a straight insertion instead of a NI USB-GPIB controller so some consideration must be given to compatibility with the software that will be talking to it. Many software vendors now support the Prologix product in the available controllers list so the situation is getting better.

If the BEIMING Technologies controller turns out to be easier to interface with software packages, it may become the new 'king of the hill', at least for as long as you can find it. If Agilent get upset by any IPR issues, we could see it disappearing off ebay at least.

[vizer]

Which controller will work best with an HP 3457A DMM? The Agilent clone?

[dfnr2]

The BEIMING Technologies GPIB controller is apparently the same functionality as the Agilent USB-GPIB units and will even accept the Agilent firmware updates ! This would indicate to me that we are probably looking at a cloned Agilent product .... IPR ?

From reading the web page, my impression was that you can use the cable to do firmware upgrades on HP devices; not that the USB-GPIB interface itself could be updated with firmware intended for the agilent USB-GPIB interfarce.  The form factor sure does look a lot like the HP device, though.

I own 3 of the Prologix devices, and they work with PyVISA.  However, as mentioned above, these are not compatible with any boxed software.  I think there would be some advantage to a good (legally reverse engineered) HP clone.

I plan to order one when I get back in town, just to check it out.

[vizer]

Aurora: Those are real issues; can an NI USB-GPIB controller clone be far behind?

dfnr2: I would be interested in a comparison of the BEIMING Technologies controller with the Prologix unit.

[mikeselectricstuff]

This thread should maybe be moved to the reviews section...

[Mechatrommer]

Simon?

[Rhythmtech]

Which controller will work best with an HP 3457A DMM? The Agilent clone?

Difficult to say, if the meter uses SCPI for communication it shouldn't matter what you use as long as you figure out how to get it talking, which is usually just making sure the enable remote command is set. I've used RS232 quite successfully with a few HP 34401A multimeters. The advantages of GPIB are not present if there is only one device and you don't really need development environment integration via a driver of some sort.  GPIB is after all just another serial interface.

Usually when you buy something like an NI GPIB card a lot of what you are paying for is the code libraries that enable you to use the GPIB device as a stand alone device in visual basic or whatever you're using to code. On the cheaper ones they often emulate a com port and you would need to build some of the interface error handling and syncing to make it work reliably in say an industrial application. The NI version has a lot of stuff worked out already and included with the card where the cheap one have hardware and in the Prologix case no driver disk was even included.  If you're just fooling around at home, then any cheap one should in theory work if you find the right recipe of commands to initiate and terminate communication between the device and the controller.

[alm]

Difficult to say, if the meter uses SCPI for communication it shouldn't matter what you use as long as you figure out how to get it talking, which is usually just making sure the enable remote command is set.

Unless you use existing software, which will usually use something like the NI 488.2 API.

I would prefer people who develop their own software (eg. Prologix) to someone just copying the NI/Agilent firmware. Prologix is also known for excellent customer support, I wouldn't expect the same for the clones. If you (vizer) want to use $$$ commercial software like Labview or VEE, or OEM software like Agilent IntuiLink (don't think it supports the 3457A), NI/Agilent libraries are required. NI tends to be preferred to Agilent (the NI emulation is less than perfect). But I would go for original hardware in that case, they are sometimes sold used on eBay for <$300.

I've used RS232 quite successfully with a few HP 34401A multimeters. The advantages of GPIB are not present if there is only one device and you don't really need development environment integration via a driver of some sort.

I don't believe the HP 3457A supports RS-232, so that's a fairly significant advantage of GPIB in this case.

GPIB is after all just another serial interface.

Except for the minor detail that it's parallel .

[saturation]

The Prologix user community is relatively small, and Abdul, someone core to the tech side of the company, is very response in looking for incompatibilities and writing fixes.  He is a regular member of hp_agilent_equipment@yahoogroups.com.

When it first was released in ~2007, a number of small annoyance cropped up and he fixed them one at time; you can find it on the release notes of each prior version.

If you control the GPIB directly via its command set, its very compatible.  Running it through LabView can be hit and miss depending on the instrument used and its drivers.  Best bet is write Abdul directly at their tech support specifying your equipment and software.

[Rhythmtech]

Difficult to say, if the meter uses SCPI for communication it shouldn't matter what you use as long as you figure out how to get it talking, which is usually just making sure the enable remote command is set.

Unless you use existing software, which will usually use something like the NI 488.2 API.

True, I suppose I assumed that if you can purchase a daq suite, you probably won't be buying cheap GPIB card anyways... 

I would prefer people who develop their own software (eg. Prologix) to someone just copying the NI/Agilent firmware. Prologix is also known for excellent customer support, I wouldn't expect the same for the clones. If you (vizer) want to use $$$ commercial software like Labview or VEE, or OEM software like Agilent IntuiLink (don't think it supports the 3457A), NI/Agilent libraries are required. NI tends to be preferred to Agilent (the NI emulation is less than perfect). But I would go for original hardware in that case, they are sometimes sold used on eBay for <$300.

Agreed.

I don't believe the HP 3457A supports RS-232, so that's a fairly significant advantage of GPIB in this case.

It was late I was lazy and didn't look it up...

GPIB is after all just another serial interface.

Except for the minor detail that it's parallel .

Oops, late night slip of my facts thanks for the correction!

[Fraser]

I see the Chinese are also offering a NI compatible USB to IEE488.2 controller:

http://cgi.ebay.co.uk/ADLINK-IEEE-488-USB-GPIB-Interface-Controller-/110452479291?pt=LH_DefaultDomain_0&hash=item19b77b153b

Almost $600 is a tad expensive for such a 3rd party device though ! Maybe cheaper versions will appear ?

[alm]

I see the Chinese are also offering a NI compatible USB to IEE488.2 controller:

http://cgi.ebay.co.uk/ADLINK-IEEE-488-USB-GPIB-Interface-Controller-/110452479291?pt=LH_DefaultDomain_0&hash=item19b77b153b

Almost $600 is a tad expensive for such a 3rd party device though ! Maybe cheaper versions will appear ?

MSRP for the NI GPIB-USB HS is $550, on eBay they're much cheaper (plenty available for $400), so the price is more than a tad too high in my opinion.