... AND FUNCTIONS:1,Our Access Controller fits any type of installations, up to 20,000 users, from ... , With RS485/232 communication 7, With free attendance online checking 8,Without power supply9,Whenever required, the data ... is set up within a few minutes. 11,In case of power failure, the back-up battery (up to ... 12V- 17 A/h) ensures numerous hours of full autonomy. 12,Power supply Box (optional)13, ...