If I can use my GPIB controller as my DAQ to control my instruments?

[elahetal]

Hi, I am a beginner in LV and need your help for morte clarification about my undrestanding:

Suppose I want to control 7 instruments( like temperature sensor, osciloscope,...) using my GPIB controler, in other words, my GPIB plays as my DAQ(am I right in this step???) the instruments doesn't need to communicate with each other but each time that I read the temperature value I make some calculation in my LV code and then decide which changes apply to the instruments for example decreasing the frequency of the signal generator, pls let me know if I can have realized my DAQ correctly?(I mean if the GPIB controler acts as my DAQ) then comment how to decide which kind of GPIB is suitable for my work 

I am really in need of your help,

Thanks 

[Dennis_Knutson]

I would not describe the controller as the DAQ. The data is actually being acquired by the GPIB instruments. The controller queries the instruments for that data and sends commands to them to control.

All of that is just semantics. What you will need to find or write is the code to communicate to the instruments.  Go to the Instrument Driver Network to search for driver, learn what they are, how to use them, and how to write your own code.

[elahetal]

Thanks Dennis for your prompt answer,

What I got from yoour answer helped somhow to have a better underestanding from what I want to do, but let me ask another question:

Considering what I described before and what u answered meI guess you know what I want to do and My set up seems complete( I mean I do not need anyother instruments to be added to my set up to  do the mangement or have a DAQ role, the GPIB along other instruments and my code in LV can run the system) but my question is that which parameters I should take into consideration while selecting the GPIB?

Thx

[Dennis_Knutson]

I don't know if you mean to select GPIB instruments or the GPIB controller. For instruments, find those that meet the specifications for the types of measurements you need to make, the accuracy, the speed, the cost, etc.

If you want to select a GPIB controller, then you have a choice between internal card (PCI, PCIe, etc.), external (USB), or for connection over distance or a newtwork, an Ethernet/GPIB controller. 

If you would explain a bit more about what you want to accomplish, then perhaps your choices could be narrowed down. You would also really benefit from contacting your local sales engineer to go over details.

[elahetal]

Thanks again Dennis

I describe you what I want to do: what I supposed to do is set up a test gear to measure the static output charecteristics of high-current power Mosfet( similar to what a curve tracer does but with more accuracy) now I know my limitation about my instruments and know how to write my code to run my

setting, my main problem is about the hardware set up. I want to run my system including an osciloscope, signal generator, temperture controller, AWG and MosfEt driver by the code I write in LV.I know that all of this instruments should be connected to my PC using the GPIB network, also I know that sending and recieving data should in the network should be controled by the GPIB controler, I know my limitations about transfer rate, voltage, current ... but for example 

GPIB-USB-HS   and  PCI-GPIB both satisfy my requirements. Now, I am wondering how I should select between these two??

The othe question is that I can not undrestand how to connect all the above instruments using one GPIB cable?

Thanks Thanks Thanks

[Dennis_Knutson]

If you have a regular pc with an available slot, I would recomend the PCI version.

You can't use a single cable to connect all of the instruments. You either use a daisy chain or star configuration. With a daisy chain, you use a cable from the controller to instrument 1, a cable from instrument 1 to instrument 2, etc. With a star configuration, you use a cable from the controller to instrument 1, a cable from the controller to instrument 2, etc.

There are some GPIB tutorials on NI's site and others. You might want to google that to learn some of the basics.

[elahetal]

Hi Dennis,

Thanks again and again for your response.

I am familiare with those configuration and I need star configuration but my problem is that when I read with papers about how GPIB works, all mention that one controller can support up to 15 instruments, it is acceptable if I can find sth like HOB that using one GPIB controler I can communicate with all instruments and make the connections but according what i found before and u mention each 24-conductor cable has both plug and receptacle connector at each end then in this case I can use one of the controllers as the mother controler and others will conect together to control each instrument, here just I want to make sure my underestandig is correct before order the  instruments.

Anyway thanks a lot for your answers.

[Dennis_Knutson]

I don't know what HOB is.

A system only has a single GPIB controller. The instruments are talker/listener and usually do not have any controller capability.

A star configuration for 15 instruments can be mechanically unsound. That's an awful lot of cables to stack up.

[dark7flame · Accepted solution]

elahetal,

If you have all of the instruments you need, you now need the following hardware (to summarize)

1) a computer.  It needs to be decently fast, especially if you are controlling 5+ machines, but it doesn't have to be amazing.

2) a GPIB card that works with your computer (PCI slot or PCIe, etc).  I HIGHLY recommend an NI GPIB card, especially if you are using it to write a labview program.  3rd party cards can complicate your life immesurably.

3) GPIB cables to each machine (if you have 2 machines, you need 2 cables).  If a machine doesn't have a GPIB connector, it can't be GPIB controlled.  It may have a RS-232 or USB control.  Those connections do not need a GPIB cable, they need their respective cables.  Some machines also cannot be digitally controlled.  A DMM from the 1960s probably doesn't have the connectors or the internal hardware to be part of your setup.  Make sure each piece of equipment can be controlled by the computer

Things I would do to get started on your LV code.

1) Download the drivers for each instrument.  The drivers are LV code that, when run, allow you to communicate with your instrument.  Some drivers come pre-assembled with interfaces that look like your machine's controls, others come with all the commands but no interface.  The quality of each driver will vary.  If no drivers exist, read extensively the instrument manual and the protocols of the connection you are using (GPIB, USB, etc).

2) Get each device working seperately.  If you can get each device to be completely computer controlled, you are 80% of the way there.  This may take a lot of time.  I know that I've taken several weeks to get each device working properly.  Once you have seperate codes and know each device can be controlled by the computer (or just dump information), then you are ready to code.

3) Build the master code by putting together the individual parts.  If you think of it like programming Fortran or C, it becomes quite easy.

As for the semantics, the DAQ is the entire setup; instruments + computer + GPIB.  Your computer is the controller and the bus is the GPIB cables where data, commands and responses are transmitted.  Read up on it.

[elahetal]

Darl7flame:

Thanks a lot for your detailed and complete answer. you mentioned to points that I really need to know. NOw I am clear about my set up due to your great comments, thanksssssssssssssss