The thing is that the v2.1 has moved the TTl to top right corner and now has three pins vs two on the original release.
It does not change how we connect the board.
I am connecting the board with a dedicated 24 v power supply and it needs to connect the GND from the new power supply to the GND of the Laser’s power supply.
The TTL GND TO K40’s Power supply’s L and if you want to drive the laser using PWM then connect the TTL’s S to the IN ON LASER’s power supply.
I am installing a two way switch, so I can decide when to use PWN AND WHEN TO USE FIX LIMITING LASER POWER OUTPUT.