Can I connect a GPIB Instrument to 2 PCs ?

[Rafi2003]

Hi,

I have a GPIB instruments that I wish to use with 2 PCs.

- They will not work at the same time
- Each PC uses different channels in the instrument.

I know that there must be only one controller in a GPIB loop. However, is there any way to use 2 PCs (2 controllers) in one GPIB loop? (May be by setting 2 different addresses?)

Thanks

Rafi

[LuI]

Rafi,

I am not aware of any solution to deactivate a GPIB controller on one PC and activate it on another, just by command.

There is, however an easy solution: Use just _one_ controller!
This is easy to achieve. Either share the device on that computer that houses the controller. Than you can use your LAN to operate the device.
OR use a GPIB/Ethernet-controller, like the GPIB-ENET/100 (http://sine.ni.com/apps/we/nioc.vp?cid=10622〈=US). It is quite expensive, but NI advertises it as 'share your equipment via LAN'.

There might be other controllers as well. Search the web!

Greetings from Germany!
--
Uwe

[Shawn B.]

Rafi and Lul,

---

@LuI wrote:
Rafi,

I am not aware of any solution to deactivate a GPIB controller on one PC and activate it on another, just by command.

---

There is a command to do this! One thing to note is that there can only be one SC (system controller) on the GPIB bus. This can not be passed around dynamically in your program. There can also only be one CIC (controller in charge) at a time, however this can be passed between devices that have controller capabilities.

There are three ways to become CIC:

1. You can use ibpct to pass control from from the current CIC to the interface you would like to be CIC.

2. The SC can call ibsic and it will become CIC without it being passed.

3. You can also use ibrsc 0 to first release CIC on the current CIC, then use ibrsc 1 to request CIC on the other interface.

These functions are of course documented in the NI-488.2 help, and there are equivalents in LabVIEW for both VISA, and GPIB VIs. You can find a KnowledgeBase that describes method 1. and 2. here. Hope this helps!

Shawn B.
National Instruments

[israelsze1]

Hello Shawn .
i read your response to Rafi2003 and the article
"Passing GPIB Control -- System Controller vs. Controller In Charge" you attached..

my question is , what the difference between Device which have controlling capability and
another system controller on the same GPIB bus , to pass CIC to it..


thanks in advance..
Simon.I

[Shawn B.]

Simon,

Is the question what is the difference between the SC and a Device that can be a controller?

Usually on a GPIB BUS you will have one GPIB interface in you computer that will act as the SC and the CIC. You will be normally be communicating with a Instrument that can only act as a talker and a listener, but not a controller.

Sometimes some instruments have controller capabilities as well. In this case the GPIB interface in the computer will remain the SC but it can pass the roll of CIC to the instrument and regain it again by using one of the methods I mentioned above.

The most common situation is that there are two GPIB interfaces in computers connected to the bus. Both devices have controller capabilities, but by default the board at Primary Address 0 will be the SC. You can also manually select who will be the SC in the Measurement and Automation Explorer by right clicking on the interface and selecting Properties. Then check or uncheck the System Controller box.

I hope that answers your question, but if it doesn't let me know.

Shawn B.
National Instruments