Communicating between computers with GPIB

[Dirk_Steel]

I've developed a system for automating processing of in-situ vacuum pumps in infrared detector dewars. The systems have been in use for several years and I'm in the middle of an upgrade and I was wondering if I can link the systems together to increase my process throughput. Each system is in a portable rack and rolls up to a vacuum oven where the process takes place. I'm getting pressure readings from an ionization gauge controller using GPIB. I have 4 systems total and I would like to try to link two together so that I can process twice as many units at a time on the same vacuum oven. Currently each system has one GPIB interface and all have the default GPIB address of 0. I know I can give each system's GPIB interface a u
nique address (0,1,2,3) but I'm not sure how to pass control between systems. Ideally I would hook up both systems to the GPIB, trigger one of the systems to search the GPIB using the Find Listeners VI to determine the other controllers address, and then pass control to one of the systems. I'm assuming I can't do this since both systems are initially controllers and this would screw up communication on the GPIB. These are utilized in a high throughput production environment by unskilled operators, so whatever I do would have to be fairly automatic. These guys can press a button to link the system, but I can't have them configuring the GPIB interface to transition to this mode. Any suggestions?

[LesHammer]

If I understand your question correctly, probably the easiest thing to do would be to get a LAN-GPIB converter (both NI and Agilent make one, so choose one that matches your VISA). Connect this to the instruments. Then each computer can talk LAN to the converter. The computers can also use LAN to lock a file or do some other type of token communication to indicate that the instruments are busy.

Les.Hammer@CompleteTest.com

[JoshuaP]

Hey Dirk,

If I understand your question you just want to have two different GPIB controllers connected to the same GPIB bus. In this case you will just have to make sure that they have different addresses and one will be set as the controller by default and then the other one can be made the controller in your application.

Here is a KB that explains this in more detail.

http://digital.ni.com/public.nsf/websearch/873BE8238AD6B0BA86256B1B004DC203?OpenDocument


However, if all you want to do is to be able to access the same GPIB bus from different systems then a GPIB-ENET/100 would work great. It resides on the ethernet with an IP address. You can access this device from any computer that is connected to your network. This allows for applications to be
run from different computers, but you can also use an iblock to only allow one application at a time to access the device.

I hope this helps out.

JoshuaP
National Instruments