Laser on/off

Hi,

I'm using a "HKO 1050" (http://www.sos.sk/a_info/resource/d/HKO350e.pdf) driver on my 445nm diode.
I've connected the main power leads to my heater mosfet and I'm controlling the laser with "M140 S255" to turn it on and "M140 S0" to turn it off.
Is there something that speaks against that procedure?

The reason why I'm asking is the driver has a TTL compatibel "shutdown pin". Is it possible to control the brightness (output power) of the laser with a pwm signal on that pin or is it just another option to turn the laser on/off?

Ok, stumbled over another datasheet for the driver which says the "TTL" pin is compatible with a so called "DIMLED" module (http://www.a1w.de/Dimledconnect.pdf). This module seems to have PWM out.
So I think I can just hook it up to a free pin on my arduino.