The digital signal portion of the CO2 laser tube power supply has various terminals for signal power, signal gnd, laser intensity and engaging the laser (turning it on or off). The TL and TH are triggers to turn the laser power on or off. These may be labeled L or H on some laser power supplies. You can use either TL/L, or TH/H to control the laser.
If you use the TL or L terminal to control the laser:
If a low signal (gnd) is present at that terminal, the laser will turn on. If a high signal (5v) is present, the laser will turn off.
If you use the TH or H terminal to control the laser:
If a high signal (5v) is present at that terminal, the laser will turn on. If a low signal (gnd) is present, the laser will turn off.
You should first test the control signal from the interface with a multimeter to make sure the laser will be controlled correctly before powering the laser power supply
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On the blacktooth machine wiring diagram for parallel breakout a wire goes from 6 on the BOB to TL on the laser power supply. My power supply has an"H" followed by a "L". Which is correct? I've connected to the "L" but the laser appears always on.