Hardware Reference
In-Depth Information
Figure 12.22 Ice flow tunnel (IFT) control application (the form was created
using MS Visio and Visual Basic)
spray control is to be provided. The system is to be controlled from a low-cost
dedicated PC controller. The test component is to be fitted with temperature
sensors so that differential readings are available for display. The overall range
of differential measurement is to be from 0 Cto20 C with a resolution of better
than 0.5% of reading and an accuracy of better than 0.5 C.
Software
Two Visual Basic 6 applications are used concurrently in this application. Visual
Basic 6 was chosen for the software development because of the ease of creating
visual controls and because the language was already being used extensively
within the department. One of the Visual Basic applications provides control for
the ice flow tunnel (IFT control) whilst the other (TDC Control) is responsible
for collecting data from the AD590 differential sensing arrangement and then
storing this for later analysis. The graphical displays were first produced using
MS Visio and then imported into the Visual Basic forms. The Visual Basic
controls were then superimposed.
The IFT control application provides slider controls for setting the air tem-
perature, velocity, and pitch angle of the component on test (see Figure 12.22).
Hardware
The PC is fitted with an ISA I/O card which has eight analogue inputs and two
analogue outputs. A further ISA I/O card provides 48 digital I/O lines arranged
in six groups of eight.
The variable speed drive (VFD) for the 10 HP fan motor requires an input of
10 V DC for frequency adjustment (over the range 0.1-400 Hz) and an airflow
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