Hi,
I am having some trouble with getting the state of all pins low when I write to my NI USB 6501 for the first time after a computer restart.
I am using the NI USB 6501 to control a series of valves via transistors. I am using all pins as outputs and I would like them to start in a low state. As it is not possible to configure the startup state of the NI USB 6501 (the pins are configured as inputs at startup) I have used a pull down resistor of 660 ohm to lower the output voltage to below the activation voltage of the transistor. When I initialize my labview program I set the pins to output and then set them low as shown below. I call this function once for each pin.
The problem is that the first time I run my program after a computer restart, all outputs are set to high even if I write low. If I immediately after this function adds an identical function to set pins to outputs and write low then all pins are set low as expected. It is also strange that this only happens after a computer restart. Unless I restart my computer I can not repeat this error.
Have anyone experienced something similar or have any ideas of how to fix this?
Thanks,
Rui