I am using a National Instruments USB-6000 DAQ to control some equipment that accepts TTL inputs.
Specifically, I have to pull a pin (normally 5V) to low. As I understand it, to do this, I can use my DAQ's digital output configured as open collector operation. Is this correct so far?
Furthermore, I'm confused as to the use of a pull-up resistor in this case. Looking at this example, there is a pull-up resistor on the path to Vcc. In my case, there is already 5V on the pin by default. So do I still need a pull-up resistor? I can only think that I would need one in series to limit the current going into my DAQ.