Trouble detecting hi/low digital input modes.

[torm]

Hello,

I am a relatively new user to LabVIEW 8.0 and I have the following problem.

I am using an NI USB-6008.  I am working with instrumentation that has software controlled limit switches.  Before moving a stepper motor, I am attempting to check to see if the limit switch has been reached in which case the circuit would be closed and I should see a ~5V input.  However, no matter what I have tried I cannot get the software to detect when this switch is closed.  I attempted the barebones coding by simply wiring the same data acquisition configuration directly into an array indicator on a front panel and even when no wires are plugged into the NI USB-6008.  Having reached this point I am not sure where I am going wrong.

I have attached the VI for my program as well as the very brief VI I made to try to check the individual port status.

Thanks so much for reading this.

[KyleP]

Have you verified that the voltage coming out of the USB-6008 when the switch is connected is in fact 5 Volts? Try measuring the voltage with an external device such as a multimeter to be sure. The 6008 is not externally powered and can only provide a small amount of current per channel.

[torm]

Thank you for replying,

I was trying to troubleshoot this issue again and I am not sure if this is the correct term but the voltages were 'floating high' in the sense that instead of a 5V charge being required to be input to view a resultant signal, it actually needed to be connected to the ground to observe an absence of the 5V signal.  With that in mind, rewiring the cables on the USB-6008 allowed for everything to work correctly.  I feel almost like one of those households calling to complain about their computer not working only to find that the computer isn't even powered on!  Nonetheless, thank you for your assistance!