@paullarson This is excellent, Paul! Thank you much.
Just to be clear, If I have nothing connected to the pwm cable from the LM controller and I have $30=1 to turn on laser mode, then $31=1000 to set max speed, then send an s1000 command, I should read 5v +/- across the + and - wires in the pwm cable.
Then, if I send s500 in UGS, I should see .28V +/- across the wires. Etc. yes?