Aquiring Data: GPIB & USB at different rates

[AlfredoT]

Hello,

I have two photodetectors connected to my computer via a NI-USB 6251 and I also have a tunable diode laser controller (ILX Lightwave LCD 3714B) which I controll with a LabView vi. I'd like to aquire the readout from the voltage NI-USB 6251 for both photodectors and at the same time record the temperature and current of the diode laser. However, the rate at which I am aquiring the voltage readout from the photodetectors is much greater than that for the current and temperature of the laser from the controller.

How do I build an array that will record the photodetector voltage and input the temperature and current values of the laser as they are aquired? I need to record these values into a .txt file and I'd like to have four columns: photodetector 1, photodetector 2, laser temperature, laser current.

Thank you. 

Message Edited by AlfredoT on 04-23-2009 11:13 AM

[Dennis_Knutson]

I don't quite understand. If you have the DAQmx Read and the VISA Read in the same loop, they will acquire at the same rate. Are they in separate loops? Or, are you saying that the number of samples from the DAQmx Read is much greater than the number of samples from the VISA Read? At the very least, post an image of your block diagram and even better would be to post the actual VI.