Data Buffer Tab. When running as an ActiveX object instanced from a parent application, the data buffering functions give control over the frequency of signaling to the parent that there is data available for upload from microDAQX. As well as signaling the parent, it is possible to perform rudimentary data logging from microDAQX, writing values to a comma delimited text file. This rudimentary data logging function will work from microDAQX running as a standalone application. The controls are shown in figure 4.6, and detailed in table 4.4 Figure 4.6, The Data Buffer Tab. A buffering cycle comprises a fixed number of data points per channel received from the microDAQ, this number of samples being selected from the 'Samples per Cycle' dropdown. The 'Raise Event' frame controls when microDAQX signals that it has data ready to be read by a parent application in terms of completed buffer cycles. The total data points collected per channel is the product of the samples per cycle and the number of buffer cycles selected. The data passed up to the parent is therefore identical for the two settings examples of 20 cycles of 100 samples or 1 cycle of 2000 samples, though in the case of the latter the parent application will receive only 1 event rather than 20. Buffering may be started and stopped by the two buttons on the form, whose function is replicated as a property over the public interface for parent applications. Alternatively, the buffering may be started and then wait for a trigger of a certain data value on a particular channel before starting the desired buffering regimen. The furthest left indicator in the upper right of the main form shows red for buffering 'on', and the central indicator blinks when a buffer cycle is complete. On the completion of this buffer cycle the signaling event is raised by microDAQX. The 'Log to Disk…' checkbox forces the appending of the last buffered data to the selected logging file whenever the Raise Event condition is met. User Control Function Raise Event options Select how often an event is raised with a parent application, or the last data is written to disk, in terms of buffer cycles. Log to Disk… checkbox Check to append values to the selected CSV file when the raise event condition is met. Start options Choose between simple on/off, or wait for a suitable data value on a channel before starting. Samples per Cycle dropdown The number of data points (per channel) comprising a buffer cycle for the purposes of calculating the Raise Event t...
