What is the typical output voltage coming out from Parallel port as I get random voltages range from 1.6-3.0V (no breakout board….directly measuring from the port)?

My understanding is TTL low is 0-0.8V and high is 2.6 to 5V.
My driver accept Pul-Low 0-0.5 V which I set “MACH3 Setup menu” STEP pulse setting at ACTIVE LOW so the drive work ok.

Yet, range of random voltage output is throwing me off…Any advice?

Thank you
Jeff