DASYLab Data Reduction with a Combi Trigger Primary Software: Other NI Software>>DASYLabPrimary Software Version: 6.00.03 Primary Software Fixed Version: N/A Secondary Software: N/A
Problem: My DASYLab worksheet acquires temperature values, and now I need a function to work only with data above 25°C. How can I reduce the number of samples based on the value? Solution: You will need to use a DASYLab Relay Module to reduce the number of measurement values based on the values themselves. The Relay removes data depending on a control signal (works sample by sample) or controlled by an Action module (works block by block). The more accurate solution is to use a control signal: this signal must be TTL high when the values should be transmitted, and it must be TTL low when the data should be removed. The best way to create this control signal is to use a Trigger module. This monitors the measurement value and sends a 0 or a 5 to the X input of the Relay. The standard trigger is the Combi Trigger module. The Combi Trigger allows you to define the start condition (trigger output is set from 0 to 5) and the stop condition (trigger output is set from 5 to 0). The output of the module is a data channel with the same timing as its input, but with only TTL Low (0) or TTL High (4) data values. In this case, the start condition is "Signal Grows Above Level" with a threshold of 25, and the stop condition is "Signal Falls Below Level" with a threshold of 25. Connect the trigger output to the X input of the relay. The resultant data output of the relay will only contain temperature values above 25. Note that the resultant data channel (the output of the Relay) is now flagged as "triggered data", implying that it may have gaps and short blocks. Many modules will not allow you to combine normal continuous data with triggered data. This is often identified by the "Time or block information at the inputs of this module do not match" error. Related Links: Attachments:
Report Date: 05/06/2002 Last Updated: 12/08/2004 Document ID: 2L5B070Z |
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