Attainable Sampling Rates when Using NI DAQmx and DIAdem DACPrimary Software: DIAdemPrimary Software Version: 8.10 Primary Software Fixed Version: N/A Secondary Software: Driver Software>>NI-DAQmx
Problem: Which Sampling Rates does DIAdem DAC Support with the NI DAQmx Driver? Solution: In DIAdem DAC, you can operate hardware that is supported by NI DAQmx drivers either in Software clock mode or in Hardware clock mode. Unclocked digital I/Os are the exception, and can only be operated in the Software mode. Analog output is also supported only in the Software clock mode. Hardware Clock ============= In Hardware clock mode, the hardware generates the clock, not DIAdem. Therefore, you only can use clock rates that the hardware supports. Which hardware you use with which modules in a measurement, may also affect the attainable clock rate. This applies for NI compactDAQ, for example, because with NI cDAQ, all the acquisition modules operate at the same clock rate. If you select a clock rate that is not supported, the driver displays a message and recommends the next highest clock rate. Software Clock ============ In the Software clock mode, DIAdem generates the clock with the Multimedia timer on the computer ("Windows Timing"). You can set this timer to the millisecond, to a maximum clock rate of 1kHz. DIAdem DAC uses a special algorithm to convert clock rates that are specified in Hz, into integer milliseconds. Therefore, the clock rate that is actually attained may deviate from the clock rate specified in the DIAdem DAC clock block. If you want to know which sampling rate was actually attained, select "Measure>>Last measurement status..." in DIAdem DAC after the measurement, or calculate the sampling rate from the difference between the time values in the recorded time channel. The following is a list of integer clock rates in Herz, which can be used without conversion:
If you want to use clock rates that are between those in the list, we recommend that you specify the clock rate in the DIAdem DAC clock block in milliseconds between 1 and 1000. You then no longer need to convert the values, and the time channel has values with only a few decimal places. For example, if you enter 3 milliseconds, which corresponds to 333.33...Hz, you get a time channel that increments in steps of 0.003 seconds. Related Links: Attachments:
Report Date: 04/20/2007 Last Updated: 04/20/2007 Document ID: 43KCEDCR |
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