No. Set $31 to 0. This is minimum spindle speed. Set $30 to 1000. This is maximum spindle speed. You can actually set $30 to whatever you want. Scienci recommended 100. I chose 1000 because I thought it gave me greater resolution. Once set you leave these alone.
From the UGS console use the following GRBL commands:
M4 - turn on the laser
Sx - set spindle speed.
M5 - Disable/turn off the laser. (Your gcode will only use M5 at the end and will use s0 to turn the laser off while engraving/cutting).
Don’t forget we are using the spindle speed controls to control the laser.
So, m4 s0 would turn on the laser at 0% intensity - essentially off but enabled.
S100 would turn the laser on at 10%
S1000 would turn the laser on at 100%
If these don’t work try issuing g1f300s0. This also sets the speed of movement. This may not be necessary, but I got an error message once that I had to set the speed.