GPIB Bus system - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: November 03, 2023, 05:48:36 pm
content: I have searched on how to connect two or three GPIB supported devices to one computer but could not find a concise answer.Multiple adapters into one USB powered hub? Connect them all to a common GPIB to usb connnector (what would be needed?).Thanks,Dewey

author: pqass
author_rank: Super Contributor
timestamp: November 03, 2023, 06:08:27 pm
content: Quote from: watchmaker on November 03, 2023, 05:48:36 pmIt's a personal preference. With the AR488project, you can have it both ways. See github pagehere, specifically AR488-manual page 44 (no output drivers), or page 45 (with output drivers that can support many GPIB bus devices). This is myimplementationof single RS232 to many GPIB devices.With commercial devices, it is more expensive to do the former.

author: alm
author_rank: Super Contributor
timestamp: November 03, 2023, 06:56:10 pm
content: At least when buying commercial GPIB adapters like NI/Agilent/Keysight or Prologix, adapters are typically more expensive than cables. So economically it makes sense to connect as many devices as possible to the same GPIB bus, within cable and device limits. GPIB implemented using proper drivers is a pretty robust bus.The other argument I can see if you're maxing out the bandwidth of a single GPIB bus.GPIB has stable addresses set per instrument using either hardware switches or software configuration, while enumeration of USB devices can be a lottery depending on OS, so it might be that at some point USB-GPIB adapters 1 and 2 will switch places. GPIB addresses are much more stable.

author: watchmaker
author_rank: Unknown
timestamp: November 03, 2023, 07:29:54 pm
content: Quote from: alm on November 03, 2023, 06:56:10 pmJust to be dense. I would buy one GPIB cable per instrument I care about, daisy chain them and terminate the last one into a GPIB>USB adapter?Thanks.Regards,Dewey

author: alm
author_rank: Super Contributor
timestamp: November 03, 2023, 07:43:46 pm
content: Quote from: watchmaker on November 03, 2023, 07:29:54 pmI would buy one GPIB cable less and plug the GPIB-USB adapter on top of a GPIB cable on the back of one of the instruments. GPIB does not dictate any particular topology and I believe it useslength limitsto limit reflections from interfering. There's no such thing as a GPIB terminator like with SCSI or Thinnet (10base2). Note that this applies to GPIB-USB adapters with proper bus drivers, not a micro controller directly driving the GPIB bus.

author: alligatorblues
author_rank: Regular Contributor
timestamp: November 08, 2023, 06:31:40 am
content: Many inexperienced users are attracted to GPIB-USB adapters, but that works best with one instrument. USB is flakey because of how it's implemented. For USB3 USB-A to USB-C cables, there are 17 different configurations. Every USB controller in PCs is implemented according to the IC used, and many implementations are incomplete or incorrect. So, you end up with USB soup.GPIB 488.2 is a very simple, robust protocol that is inflexible in the way it is implemented. So, it's always the same. And it is made specifically for T&M instrument remote control. So, for hardware setup I just install a PCIe GPIB adapter in an empty slot in the motherboard, and chain together the instrument system. Then I have one connection to the PC.Next, I install the driver for the GPIB card, and check if it shows up. I use Linux, so I use the lspci command. Then, I install ivi-c drivers for each instrument, at least one of which will include the VISA agnostic hardware abstraction layer. For beginners, MatLab or Labview can make automation of tasks much easier.The material on this pagehttps://www.ivifoundation.org/resources/default.aspxcan be very useful.