If you set the time 30 min on /30 min. off 1 - change the dip switch settings for off time 1,2 dip switch for on time 6,7 dip switch for time setting in hour 1 dip switch is off and 2 dip switch is on (off time) 6 dip switch is off and 7 dip switch is on (on time) after that select multiplier If you choose multiplier is 1 3 and 8 dip switch both on Total time adjustments is done by potentiometer knob up for off time and down for on time setting total 10 div. time setting in hour 1div. =0.1 hour 10 div.=1 hour For half hour on and off both the potentiometer knob is set on 5 div. 5×0.1=0.5 hour ,1hour =60. min. 0.5 ×60= 30min that's all