Bias Circuit

Unit A. Communicating with the Circuit
Board: LabVIEW Programming and
Measurement Exercises
Communicating between the computer and a circuit board (sending and receiving voltages
from the computer) is accomplished with the data acquisition card (DAQ). The DAQ is normally
connected from the computer to the circuit board with a 68-pin cable. In general, all 68 pins
are used for such things as analog inputs and outputs, triggering, digital inputs and outputs, a
5-V dc supply, and counters. In our projects, we use, for the most part, only analog inputs and
outputs. A digital output could also be used if we required an additional output, which of
course is limited to on or off.
Since the analog inputs and outputs involve digital-to-analog and analog-to-digital
conversions, special consideration must be given to the discrete nature of the conversion
relations. These are discussed in the following along with a series of basic programming and
measurement exercises. A sequence of VIs (virtual instruments) is programmed. In Unit A.2
and beyond, preprogrammed VIs are used.
The LabVIEW library, ProjectA.llb, of Project A contains the preprogrammed VIs, along with
samples of all of the VIs in the exercises. Project A complements this unit. It is recommended
that the parts of Project A be completed at the end of a given programming segment in the
unit. The appropriate project part is flagged as with the following:
Project PA.x (Title of Project Segment)