current source

[SCOTTIE]

Hi,

Currently I'm using LabVIEW to control a current source (Keithley 6430 SourceMeter)to send a certain current. However, if we want to connect a current source IC instead of the cumbersome machine, do you guys know any easier solution? I asked some people and they told me I have to use assembly language to program that kind of ICs. Is there any way that we can easily do it by LabVIEW?

PS: LabVIEW 6.1
O/S: Windows XP


Regards,
Scottie

[tbob]

You don't mention what current source IC you plan to use. However, you will have to build your own circuit to use an IC. The IC itself will need a power source. You would need to have a relay to turn the output on and off. Then you would have to build some circuit to allow communications between the IC circuit and the PC. Then you would have to write a communications program DLL that Labview could call. This is a MAJOR undertaking and will not be easy. I suggest you stick with the cumbersome machine.
If you still want to proceede with your IC and you won't be varying the current, you could build your circuit and connect the output to a relay. Labview can then control the relay either throught the parallel port (see Labview example on parallel port), or through a DIO that you would have to buy.

[Process_Systems]

There is a relatively simple hardware circuit that functions as a current source, and can be controlled by a voltage output from a D/A card. You only need a card that will produce a voltage, say of 0 to 10 volts DC (very common), and a 3-terminal adjustable voltage regulator IC ( like the LM 317 or something similar). Instead of a fixed voltage reference to the IC, you provide a 0 -10 Vdc reference from your D/A output, cotrolled by Labview. You then choose a fixed load resistor for the regulator such that it gives the required adjustable current through the fixed load as the drive voltage to the IC is varied.
Where do you put your output terminals for constant current drive output?? You insert the terminals in series with the Negative power supply line to the IC regulator.
If you are having trouble seeing this, drop me an e-mail at dgcontrols@sympatico.ca, and I can put together a quick sketch for you. I just don't know how to draw in this input box.

Dave