Workshop 2: Using LabVIEW to Program a Computer Interface

The flowchart of a basic program to take multiple thermocouple readings is shown on the right. Using this as a guideline, the students will work in teams of three to make their computer interface. The requirements of the program are:

• multiple channels (thermocouples), specified by the user
• a switch to stop the program at any time
• save the data as a spreadsheet file
• graph the data on screen, updating at each data point
• design the program so that the data rate matches the sampling rate of Fluke Helios (1 data per second)

Optional features of the program are:

• initialize and configure Fluke (this can be done manually)
• start and stop scan mode (this can be done manually)
• add an option to NOT initialize (if the Fluke has already been initialized, this saves some time)
• add an option to NOT save

Two sub-VI's will be provided, one to initialize and configure the instrument, and one to read data for one scan from the instrument and return as a 1D array of data from all channels.

The LabVIEW tools needed to write the program are:

• For Loop and/or While Loop
• Sequence Structure
• Time VI's - Tick Count or Wait
• Initialize Serial Port
• Write to Spreadsheet
• Write to Serial Port
• Boolean Switch
• Graphing Tools
• Using Sub-VI's

A quick reference sheet will be given with descriptions of each of the above functions. During the workshop, they will use the "virtual" sub-VI's, which have the same wiring terminals as the actual sub-VI's but returns simulated data. This allows the groups to test their program without the actual Fluke Hydra being connected. Once their program is propertly debugged and working, they can test the program using an actual instrument simply by replacing the two "virtual" sub-VI's with the actual ones.