Get That Data

Photon can be useful for real-time display of data in data acquisition applications and for process control. Using the AppBuilder visual-application designer, you can write an application that intercepts events coming in asynchronously and displays them graphically in any desirable fashion.

Because the default QNX scheduler lets you schedule real-time events, data acquisition can be real time. (If you don't like the default scheduler, you can write your own--it runs in user space). Photon is capable of updating the display faster than the display's refresh rate. This is a waste of CPU cycles, because it has to wait for the display to update before you can see any changes. Thus, it makes sense to constrain Photon data acquisition events to correspon d to the display refresh rate (e.g., 72 Hz).

Process control can work in reverse. As data comes in and is displayed, events can be generated in the other direction. You can generate a touchscreen or light-pen pointer event, to which a control process is opaque. The control process translates the light-pen event into an appropriate control signal, which Photon then transmits out through a port to an instrument that can respond to it.