Difference between 'GPIB to USB' and 'RS232 to USB' adaptors

[LTBALAZS]

Hi,

I have an instrumant of which has communication issue. I was recommended to use GPIB communication instead of serial one.

My PCI socket GPIB card is incompatible with motherboard, so i cannot use it.

Would it lead to the same result if i used 'GPIB to USB' instead of 'GPIB to GPIB'?

Anyway, is GPIB to USB the same as RS232 to USB?

Kind regards,

Balázs

[GerdW]

Hi Balazs,

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@LTBALAZS wrote:

Would it lead to the same result if i used 'GPIB to USB' instead of 'GPIB to GPIB'?

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What is a "GPIB to GPIB"?

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@LTBALAZS wrote:

Anyway, is GPIB to USB the same as RS232 to USB?

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No, GPIB is something completely different than RS232! (parallel vs. serial…)

I think you need to reword your questions to make your intentions more clear…

[LTBALAZS]

Okay, to clerify this:

Connector type on computer side	Connector type on instrument side	Result
RS232	RS232	Communication stucks after hours of data acuisiton. Computer must be restarted or instrument unplugged to solve communication issue.
USB	RS232	Communication stucks after hours of data acuisiton.Computer must be restarted or instrument unplugged to solve communication issue.
GPIB	GPIB	Not yet tested due to oncompatible socket type on computer side
USB	GPIB	Not yet tested

When using GPIB -> USB converter we convert parallel communication to serial. Will it be as reliable as if i would use RS232 ->USB adapter?

I can only see the difference in price of using GPIB to USB converter which costs a lot more than a RS232 to USB converter.:

https://hu.farnell.com/ni/778927-01/gpib-instrument-control-device/dp/3621284 

Why should i choose this rather than a cheap RS232 to USB converter?

[GerdW]

Hi Balazs,

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@LTBALAZS wrote:

When using GPIB -> USB converter we convert parallel communication to serial. Will it be as reliable as if i would use RS232 ->USB adapter?

I can only see the difference in price of using GPIB to USB converter which costs a lot more than a RS232 to USB converter.:

https://hu.farnell.com/ni/778927-01/gpib-instrument-control-device/dp/3621284 

Why should i choose this rather than a cheap RS232 to USB converter?

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Any kind of USB-2-xyz converter suffers from the same USB limitations regarding

• stability of the communication bus
• interference with OS settings (like power savings settings)
• speed in terms of "single sample readings" (aka request-response type) and "timed sample readings (aka streaming larger data blocks), with USB suffering also from connecting several devices on the same USB bus

On the other hand I had no problems to run setups for several hours using a USB-2-GPIB converter from Keithley. When the GPIB network is setup correctly, using good GPIB cables with good connectors, then it is very reliable IMHO.

The price tag is quite different because the GPIB is not as wide-spread as the RS232 bus: there is a huge difference in production volumens leading to this different price tag! The same applies for PCI(e) cards providing RS232 or GPIB ports…

GPIB allows very easy connection of upto 15 devices on the same GPIB port, which is rather "uncommon" for RS232. Back in the days the transfer speed on GPIB was better than on RS232, but nowadays with 2MBaud RS232 connections this might be nearly on par…

[AeroSoul]

Considering that your communication runs fine for hours and then gets stuck i'd assume you have a VI set up wrong, so it hogs the memory/CPU.

[rolfk]

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@AeroSoul wrote:

Considering that your communication runs fine for hours and then gets stuck i'd assume you have a VI set up wrong, so it hogs the memory/CPU.

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Or Windows power saving settings kicks in and disables the USB adapter. There is not much information in the OP's post to go further than guessing. USB adapters have often the problem that Windows power saving settings disturb it and disabling that is usually a good idea for such adapters when using them for long duration tests.

The problem is that the according drivers are usually not setup to detect such Windows power management interruptions and just keep trying to the now disabled device. Only when reopening the device do they sometimes enable the device again (and sometimes not even then).

Your guess of a programming error like accumulating more and more data until the process dies is of course another possibility, but the fact that restarting the device OR the application would sound not like be caused by such a problem, but again without having more information and seeing some real code, it is all guessing.