beginner

Hello everyone! I am a beginner in Labview programming and I have question regarding analog and digital signals. I am going to make a Labview program that control a laboratory device (electrode). This electrode detects oxygen evolution. However, I want to use my Labview interface in order to record the signal and monitor values of the electrode generated signals. The problem is that I have a pc-computer card with a digital output signal (National instruments NI-PCI-6534 (Digital I/O)) whereas the output signal from the electrode is analog. I would like to know if it is possible to convert the analog electrode signal into a digital one? Are there any devises available that convert analog signals into digital signals? Another possibility is of course to use a card that accepts both types of ingoing signals (analog and digital). I wonder if anyone knows if there is such card available that are fairly cheap? I would be very grateful if someone could give me some tips and advises regarding my signal trouble.