Pulse Width Measurement Using 9513 Counters Requires an Input of at Least Two Pulses Hardware: Legacy DAQ Devices
Problem: I don't measure the correct pulse width value if I perform measurement on a single pulse input. I am using the example programs for pulse width measurements provided in LabVIEW (or LabWindows/CVI). The duration for which the pulse remains high (10ms or 1s) does not change the behavior. I am using a 9513-based device, like the PC-TIO-10 or the AT-MIO-16 series. Solution: The 9513 counters requires one pulse to load the count register so that the count values can be transfered the register. Therefore, you need at least two pulses to perform a correct pulse width measurement. A related KnowledgeBase document offers more information on the 9513 counter operation. To avoid this problem, always perform the measurement on a pulse train with 2 or more pulses. This behavior applies only to the 9513 counters on the PC-TIO-10 and legacy boards (AT-MIO-16, AT-MIO-16L etc.). You can perform accurate pulse width measurement with just a single pulse input with the DAQ-STC counters. DAQ-STC counters are available on our E-Series boards (AT-MIO-16E-2, etc.). Please refer to the NI-DAQ User Manual for PC Compatibles (at the Related Link below) for more information on pulse width measurement. Related Links: Product Manuals: NI-DAQ User Manual for PC Compatibles Version 6.9.1 Attachments:
Report Date: 02/02/1998 Last Updated: 06/30/2004 Document ID: 161FKNRX |
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