34401a interface to PC - RS232 or GPIB?

[motocoder]

I recently picked up a used Agilent 34401a DMM off of eBay. I love the meter and want to take advantage of it's remote control capability.

The meter has RS232 and GPIB interface, neither of which my PC has. I do think I have a USB -> Serial converter lying around somewhere, so I was thinking I would use that. Another option would be to get some sort of GPIB to USB converter or a GPIB board for my PC.

Is there any advantage to going the GPIB route here?

Thanks

[Dave]

GPIB is bulkier and more expensive, but faster and more reliable. If you are going to use slow datalogging, you might get away with RS-232, if you want to take advantage of 34401A's fast sampling rate, you are going to need GPIB.

ASCII readings to RS-232     55/s
ASCII readings to GPIB     1000/s

[motocoder]

GPIB is bulkier and more expensive, but faster and more reliable. If you are going to use slow datalogging, you might get away with RS-232, if you want to take advantage of 34401A's fast sampling rate, you are going to need GPIB.

ASCII readings to RS-232     55/s
ASCII readings to GPIB     1000/s

Dave - thanks. Do you have any recommendations regarding how to interface my PC to GPIB? I see a number of used Agilent GPIB to USB converters (cable plus a small converter box in one) on eBay, but they are relatively pricey (~$150).

[Dave]

I suggest you pick up Agilent 82357B. They aren't cheap (about $150, as you already figured out), but they work well.

[motocoder]

That actually seems to be the cheapest option. I am curious what the device is exposed as in Windows and Linux? Does it look like a serial port? Are there going to be driver issues in newer versions of Windows?

[Galaxyrise]

Do you actually know that you have need of more than 55/s?  I wouldn't spend $150 without an actual use case in mind when a rs232->usb adapter is so cheap.  And if you want fast readings but in short bursts, you can store them into DMM memory and then drain then out via rs232 post capture.  There's enough memory for 512 readings.

All my logging has been done with the meter in 6-digit mode, so rs232 was fine.

[motocoder]

I don't have a use case where I need that at the moment, and in fact I will probably start wth RS232. Still I wanted to research the topic in case I need to go GPIB in the future.

[motocoder]

So armed with the Agilent part number (82357b), I was able to find some info on the web about this. So GPIB is a very low level, simple hardware interface. That can be mapped to USB in any number of ways. The specific protocol on the PC side is as important and the hardware interface, as it determines what PC software is going to be compatible with it.

Dave is right that the 82357b is the way to go, as the protocol this uses appears to be supported fairly widely. Note that there are also some Chinese clones of the 82357b that in theory should work as well. However, given the small cost difference, it's probably better to go with the Agilent part.

There is also an alternative from Prologix, but seems like support for that isn't as widespread.

[davorin]

If you even want to go cheaper then there is a Prologix clone and firmware reports itself as Prelogix (o;

One version was published in the Elektor magazine...and the one I use now can be found at:

http://www.dalton.ax/gpib/

Though soldering iron is needed (o;

[motocoder]

If you even want to go cheaper then there is a Prologix clone and firmware reports itself as Prelogix (o;

I would be concerned about driver support. Seem like Agilent are keeping their drivers up-to-date for latest versions of windows.

[davorin]

Well..you're right (o;

If someone for example can afford LabView then there is no need to go for a cheap GPIB-USB adapter...

But there are also some people who can't afford it...so it also makes sense to go with a cheap or self-built adapter ;-)

[neslekkim]

What about this one?

https://www.tindie.com/products/galvant_industries/gpibusb-adatper-rev3/

And those agilents, can those be used with other gpib stuff?, say Keithley 2000 series?

[davorin]

Looks nicely built....similar to the other project I mentioned..only difference is it uses a PIC18F4520 (no internal USB) instead of the PIC18F2550. Seems like a small FTDI USB-to-seriel chip there as well...
Think the main reason is that other projects are based on a sample USB code from Microchip, which can't be modified and published together.

Another difference, proper GPIB line drivers...but then again...this would also require external 5V supply as the USB can only deliver 0.5A, whereas driving the maximum allowed devices needs more power...

The advantage of the PIC18F2550 version is, that you can specify any baudrate you like, as there isn't any ;-)

[AlfBaz]

And those agilents, can those be used with other gpib stuff?, say Keithley 2000 series?

Yes.
The GPIB side is just that GPIB, so if an instrument has a port for it it'll work.

@motocoder
You mentioned Linux, if you plan to use it on that OS you may want to look into it further not sure if the  82357B works well or at all in Linux (driver issues)

If Linux is an OS you may need look for posts by a member here that goes under the name Bingo600. He's had success with one of the cheaper, third party adaptors and posted updates or at least instructions on making updated drivers on Linux including example python scripts for data logging

[AlfBaz]

Cant find the link right now but he also managed to get the particular usb/gpib adapter he had to work on a RASPi storing data on the sd card

[AlfBaz]

@motocoder
You mentioned Linux, if you plan to use it on that OS you may want to look into it further not sure if the  82357B works well or at all in Linux (driver issues)

Scrap that, it appears the 82357B is fine on Linux.
Here's the post about it, the raspi and other assorted Linux things
https://www.eevblog.com/forum/reviews/using-a-raspberry-pi-with-linux-gpib-and-a-beiming-or-agilent-usb-gpib-adapter/

[Dr. Frank]

I recently picked up a used Agilent 34401a DMM off of eBay. I love the meter and want to take advantage of it's remote control capability.

The meter has RS232 and GPIB interface, neither of which my PC has. I do think I have a USB -> Serial converter lying around somewhere, so I was thinking I would use that. Another option would be to get some sort of GPIB to USB converter or a GPIB board for my PC.

Is there any advantage to going the GPIB route here?

Thanks

Well, your PC normally has RS232 on the mainboard, only the D sub ( DB 9) plug is not assembled on the rear panel of your PC.

If you have some D sub 9 jacks in your stock, then it's cheap and easy to interface the HP34401A.

Decades ago, I even connected an HP48SX calculator to this instrument, so I think, the minimum 3 lines interface (RX, TX, GND) is sufficient for steering.

If you go for GPIB, you may better pick a National Instruments PCI bus card.
As surplus they may be available for less than 100€/$, plus cable(s).
That's much better, and you later can extend your system with other instruments.   

Frank

[macboy]

Dave - thanks. Do you have any recommendations regarding how to interface my PC to GPIB? I see a number of used Agilent GPIB to USB converters (cable plus a small converter box in one) on eBay, but they are relatively pricey (~$150).

I recommend the Agilent USB GPIB. I haven't used mine much, but it seems to work very well so far. In contrast to lower cost (Prologix) or home-made ones, this one has VISA drivers, GPIB32.dll, and an Activex component for scripting (I wonder if I'm the only one using that...). This adapter will work with Agilent software, as well as Labview, etc.  I got mine for a little less than $150 shipped from the far east, and it was brand new in a factory sealed box.

[AlfBaz]

If you go for GPIB, you may better pick a National Instruments PCI bus card.
As surplus they may be available for less than 100€/$, plus cable(s).
That's much better, and you later can extend your system with other instruments.   

I considered the NI internal cards over agilent's usb offering but the mobility of a usb adaptor (laptops etc) won me over

[davorin]

Besides the fact that many GPIB cards found on ebay are either PCI or ISA bus only...

Think I will order one of those "strange" 82357B adapters from China and crack it open to see what's inside (o;

[bingo600]

Besides the fact that many GPIB cards found on ebay are either PCI or ISA bus only...

Think I will order one of those "strange" 82357B adapters from China and crack it open to see what's inside (o;

Make sure you order a Beiming USB->GPIB
This one is compatible with the Agilent Adapter , under both Windows & Linux , even uses their drivers.

Don't get the "gold clone" it won't work on linux

http://www.ebay.com/itm/S82357-GPIB-USB-interface-Agilent-82357B-compatible-/181438006375

F is faster gpib->usb xfer (it uses DMA internally)
http://www.ebay.com/itm/F82357-GPIB-USB-interface-compatible-with-Agilent-82357B-/181438007391


And AlfBaz got my RasPI Thread correct (Where i test both the Agilent & the Beiming using linux-gpib on a RasPI)
https://www.eevblog.com/forum/reviews/using-a-raspberry-pi-with-linux-gpib-and-a-beiming-or-agilent-usb-gpib-adapter/

Well actually to be fair , the Beiming has a slight advantage on linux , as you don't need to load the Agilent firmware onto it via usb. It's already on it.
But using fxload it's not much of a problem to load it if getting a real Agilent 82357B , don't get the A.



/Bingo

[davorin]

Is there any documentation of the Beiming adapters how to control them directly under Linux?

Like there are docs/sample code available for the Prologix adapters...or the Prelogix clone firmware where I can do a simple

HCSU DEV,BMP
SCREEN_DUMP

and write the output to a bmp file...

Wonder if there is a big difference in speed when dumping the BMP file from My LeCroy 9354AL either with the S or F version.

Do you have experience with similar DSOs?

[motocoder]

Looks nicely built....similar to the other project I mentioned..only difference is it uses a PIC18F4520 (no internal USB) instead of the PIC18F2550. Seems like a small FTDI USB-to-seriel chip there as well...

Think the main reason is that other projects are based on a sample USB code from Microchip, which can't be modified and published together.

Another difference, proper GPIB line drivers...but then again...this would also require external 5V supply as the USB can only deliver 0.5A, whereas driving the maximum allowed devices needs more power...

The advantage of the PIC18F2550 version is, that you can specify any baudrate you like, as there isn't any ;-)

Looks like the FTDI chip is an FT230X. THat's really too bad. I wish more people would use an FT232H. You can get a lot more throughput out of it, and because it comes with a DLL that abstracts the driver, you don't need to write a custom driver for it. There's even an open source equivalent.

[motocoder]

Cant find the link right now but he also managed to get the particular usb/gpib adapter he had to work on a RASPi storing data on the sd card

Sort of an extended data logger? Pretty cool.

[bingo600]

Is there any documentation of the Beiming adapters how to control them directly under Linux?

The Beiming is like the Agilent , controlled by linux-gpib.
Look up the doc for linux-gpib
http://sourceforge.net/projects/linux-gpib/files/latest/download?source=files

Another program that uses linux-gpib is gpib-utils
http://sourceforge.net/projects/gpib-utils/files/latest/download?source=files

This one shows nice examples of how to program via linux-gpib.

I'm currently using playing with python for accessing my instruments via linux-gpib , as there areseveral language bindings built into linux-gpib.

/Bingo