I have a pretty old device connected to computer with GPIB (IEEE 488 standard), the bandwidth is limited so it is pretty slow to transmission 1MB data. I wonder if it is possible to boost the transmission speed.

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    \$\begingroup\$ It's probably worth mentioning the device you're connecting to and even better if you can find out the GPIB revision that it supports. I don't have access to the IEEE standards but I believe the maximum speeds changed between versions and presumably there wouldn't be much you can do on the device end if that's the limiting factor. \$\endgroup\$ – PeterJ Aug 29 '13 at 4:10
  • \$\begingroup\$ The speed limit could well be down to the lack of processor power in the device if it's quite old. But +1 for "please tell us what the device is". \$\endgroup\$ – John U Aug 29 '13 at 8:12
  • \$\begingroup\$ One of the first things you should do is see what is taking time, for example by logging timestamps of the operations. If you are using the NI Visa libraries I think there is something built in for doing this; if you are doing you own you can add it, if you have some other closed solution, no idea... \$\endgroup\$ – Chris Stratton Aug 29 '13 at 15:25

The original standard allows speeds up to 1 MBps, and the HS-488 standard allows up to 8 MBps. That being said, bus speed is sensitive to things like cable length, the number of devices on the bus, etc.

Most GPIB interface software (NI Measurement and Automation eXplorer, etc.) allow you to set the maximum speed and various latency adjustments for the GPIB interface. Try to shorten your cabling as short as possible and play with the interface settings to find the fastest stable speed your instrument can support.

If you have multiple instruments, it's best to wire them in a 'star' configuration with the host interface at the center (a separate cable from each instrument goes to the host interface) so that the minimum host-to-device distance is achieved. Sometimes geography and topography forces you to do other things like a daisy-chain bus with all the instruments in series. (Paralleling more than 3 GPIB cables can become unwieldly).

It's also not a good idea to join GPIB cables in free space (that is to say, make your junctions at an instrument, don't just plug two cables into each other) since they tend to pull apart if they're not bolted to an instrument, and partially disconnected cables introduce all sorts of bus weirdness into the mix (corrupt data, hang-ups, etc.)

I've noticed that buses with many devices sometimes need their maximum speed set lower than those with fewer devices - most likely a signal integrity situation (total bus loading).

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  • \$\begingroup\$ Is HPIB same as GPIB? It seems that it use HPIB instead but as mentioned in spec, the transfer speed could be go up to 8MBps, I tried to transfer about 300kB data but it tooks about 30 seconds. The cable is pretty short, just about 1meter. But I have two devices connected in serial with HPIB connector, will it cause the delay or slow the data transfer? \$\endgroup\$ – user1285419 Aug 29 '13 at 4:34
  • \$\begingroup\$ It is. HPIB was the name given to the standard by its original inventor, Hewlett-Packard, before it became standardized. \$\endgroup\$ – Adam Lawrence Aug 29 '13 at 11:56
  • \$\begingroup\$ I have two devices connected to the same GPIB card, installed in the computer. One cable connect the computer card terminal to one device (say GPIB-A), another cable connect the GPIB-A to the other device (say GPIB-B). So you suggest to connect them and joined in the computer card, don't you? Will it be better if I use two GPIB card, each for one device? \$\endgroup\$ – user1285419 Aug 29 '13 at 12:31
  • \$\begingroup\$ No need for two cards. Run one cable from each device back to the PC. \$\endgroup\$ – Adam Lawrence Aug 29 '13 at 12:36
  • \$\begingroup\$ Stacking more than 3 connectors is actually against the spec, so you can only do so much with a star topology. I have always tried to stick the to daisy-chain connections. \$\endgroup\$ – The Photon Aug 29 '13 at 14:59

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