Controlling many GPIB's

[terwelu]

You are right Dennis. After reading more closely, yes, "Your computer is the controller no matter what." Actually,my concern of using ethernet device is simply by port-availability from my notebook/PC. I don't have parallel/serial port. So, my choice is limited into USB or Ethernet. So if you said "All that you are doing with the ethernet device is extending how far away you can place the instruments from the controller.", regardless how many meters can I get using Ethernet, I still need something to convert the controller signals from my computer into GPIB signals, right ? It's just by coincident that I choosed Ethernet rather than USB for converter. 

Back to my project. I have two labs. Each lab consists of several GPIB equipments (but not more than 14 devices in total) and the distances between that two labs is around 15-20 meters.Could you give me your suggestion about what kind/type of devices or connectors should I use to be able to handle those GPIB devices with one computer only ?

Sorry for the misunderstanding and thanks for your concern.

Ricki

[JÞB]

terwelu

The GPIB standard allows for up to 15 devices + a controller per bus with a maximum of 20 Meters of total cable length and at leat 2/3 of the instruments powerd on.

So, you will need an ethernet to GPIB adaptor at each test location so that seperate busses can be established.  Your PC then selects the desired instrument to talk to by BUS and ADDRESS.  If your equipment is spread out in any one location you may need to have more than 1 ethernet to GPIB adaptor in each lab so that you don't violate the 20 Meter maximum cable length per bus.

[Dennis_Knutson]

Since the maximum cable length in a GPIB system is 20 meters, you will have to use some sort of extender and the ethernet controller is one such option. The are devices that extend the USB bus but I have no idea how well they work (if at all) with the NI USB GPIB controllers. That might be a separate question that you want to ask.

With two different labs, you might consider a local pc in one lab and an extender to the second. You could have two Ethernet/GPIB controllers, one going to each lab. One remote pc with an Ethernet/GPIB to one lab and and extender to the second. There are a lot of different combinations and you should consider contacting your local NI Sales Engineer so that the site can be examined in detail with the different options/costs explained.

[terwelu]

Thanks Jeff and Dennis !

I'll consider the distance limitation in my project. I'll also probably contact NI for other possibilities.

Yup, time to move on into the reality ! I'll share my experience when my project is complete.

Thanks again !

Regards,

Ricki