MASTER UNIT FOR THE CONTROL OF ANY OTHER EXPANSION UNIT (NOT COMPATIBLE WITH: MI8O4, MO4L AND MA4), CAN ALSO WORK AS STAND-ALONE. AS MASTER UNIT: TO CONTROL A MORE COMPLEX SYSTEM PROVIDING PROTECTION FOR BIGGER MACHINERIES WITH MULTIPLE SENSORS. AS STAND-ALONE: TO CONTROL SMALLER MACHINERY CONNECTING WITH UP TO 4 SAFETY DEVICES, I.E. 1 SAFETY LIGHT CURTAIN, 1 E-STOP, 1 MAGNETIC SENSOR AND 1 TWO-HAND SWITCH