Real-Time Windows Target

I/O Driver Characteristics

The Real-Time Windows Target uses off-the-shelf I/O boards provided by many hardware vendors. These boards are often used for data acquisition independently of the Real-Time Windows Target. In such environments, board manufacturers usually provide their own I/O device drivers for data acquisition purposes. This use differs significantly from the behavior of drivers provided with the Real-Time Windows Target.

In data acquisition applications, data is often collected in a burst or frame consisting of many points, perhaps 1,000 or possibly more. The burst of data becomes available once the final point is available. This approach is not suitable for use in automatic control applications since it results in latencies equal to 1000 * Tsample for each point of data.

In contrast, drivers used by the Real-Time Windows Target capture a single point of data at each sample interval and considerable effort is made to minimize the latency between collecting a data point and using the data in the control system algorithm. This is the reason why a board that specifies a maximum sample rate (for data acquisition) may be stated to achieve sample rates well in excess of the rates that are achievable in the Real-Time Windows Target. For data acquisition, such boards are usually acquiring data in bursts and not in a point-by-point fashion which is more appropriate for stable control systems.

Using Analog I/O Drivers

Normalized Scaling for Analog Inputs