I cannot achieve the advertised acquisition rates of the SC-2040 Primary Software: LabVIEW Development Systems>>Full Development SystemPrimary Software Version: 7.1 Primary Software Fixed Version: N/A Secondary Software: N/A Hardware: Signal Conditioning Other>>SC Analog Accessories>>SC-2040
Problem: I have an E-series data acquisition (DAQ) board, and an SC-2040 Differential Amplifier. I acquire data on two channels, and the maximum sampling rate I can achieve is 12.5 kS/s. According to the formula, the maximum sampling rate for two channels should be 38 kS/s. The sampling rate I am achieving corresponds to using eight channels, not two. Solution: To resolve this issue in LabVIEW, use the attached file, Acquire N Scans (2040).vi. This VI is a modified version of the Acquire N Scans.vi example that ships with LabVIEW. Due to a bug in NI-DAQ, users of SC-2040 accessories with certain E Series DAQ devices cannot achieve the maximum scan rate permitted by their hardware. This VI works around this limitation by using the internal E Series signal SCAN_IN_PROGRESS to control the track-and-hold line on the SC-2040. This example will only work if the SC-2040 is NOT listed as an accessory in the Measurement & Automation Explorer configuration utility. Unfortunately, since the configuration utility is unaware that the SC-2040 is used, NI-DAQ cannot account for the gain settings on the SC-2040. Therefore, if any channel has a gain other than one, the programmer must perform gain scaling within their VI. This example assumes that all channels have a gain of one. For NI-DAQ, follow the same instructions as listed above, but use the Select_Signal function to route the ND_SCAN_IN_PROG signal to PFI7: Select_Signal(daqDevice, ND_PFI_7, ND_SCAN_IN_PROG, ND_LOW_TO_HIGH); Related Links: Attachments:
Report Date: 07/29/1999 Last Updated: 06/17/2004 Document ID: 1NSCLLEO |
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