I want to control a simple valve driver circuit I have with a TTL logic
signal from my computer. I downloaded the basic VI:
Download - Access_Parallel_Port_with_VISA.llb
that allows me to change the voltage on 8 of the pins on the parallel
port. I can change the voltage on a given pin but it toggles
between roughly 0 volts and .26 volts. A couple questions:
Q1: What is considered TTL logic? Is it 0 to 5 volts with an upper and lower threshold voltage level?
Q2: If someone has been able to send digital I/O signals with
voltages giving a TTL logic "high" or "low", could you tell me how you
did it?
Perhaps outputting 0 and .26 volts is normal and people are just
somehow boosting the high voltage. I'm not an electrical engineer
so I have to learn this stuff the hard way.
Thanks to anyone who takes the time to reply!
shawn
