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Virtual Channels Give Incorrect Readings of 0.0 V from a DAQPad-6020E When Used on a Toshiba Satellite Laptop

Primary Software: Driver Software>>NI-DAQ
Primary Software Version: 6.6.0
Primary Software Fixed Version: N/A
Secondary Software: N/A
Hardware: Multifunction DAQ (MIO)>>E Series>>DAQPad-6020E for USB w/Mass Term, Multifunction DAQ (MIO)>>E Series>>DAQPad-6020E for USB w/BNC Term

Problem: I created an analog input virtual channel for my DAQPad-6020E, which works fine in the Test Panels; however, when I try to use that same virtual channel in a ComponentWorks application that I wrote in Visual Basic, then that virtual channel returns a value of 0.0 V. If I use standard channel strings, then the values are read correctly.

I decided to check the virtual channel again in the Test Panels, but now it reads 0.0 V there, too. I tested the resources for the DAQPad-6020E and I got a "Device not responding to first IRQ level" error message. I have NI-DAQ 6.6 installed.

Solution: This behavior has ONLY been reproduced on Toshiba Satellite laptops (e.g., the Toshiba Satellite 2100 DCS and the Toshiba Satellite Pro 440 CDT). This has not been a problem with desktop computers or laptops from other vendors. The problem commonly occurs with virtual channels used in LabVIEW examples, too, not just ComponentWorks code.

The cause of the problem is the NEC USB Open Host Controller (E5-E11) found in the Toshiba Satellite laptops, which cannot handle fast USB transfers. The USB specification calls for transfer rates of 1.2 million bytes/second. The DAQPad-6020E usually transfers data at 200 to 500 kilobytes/second. In our tests the NEC USB Open Host Controller failed at about 40 kilobytes/second. Also, once the controller fails, it remains in a error state until it is reset, which means that you must reboot your laptop.

Your choices for solutions are:
  • Use a different type of computer.
  • Use a PCMCIA to USB adapter card (which typically costs $60-$80), instead of the built-in USB port on your Toshiba Satellite laptop.


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Report Date: 02/29/2000
Last Updated: 06/28/2004
Document ID: 1US8PAB2

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