Access controllers communicate with readers that are connected to them and consequently recognise the identification card users and manage electric locks, ensure the powering of readers and an auxiliary battery power supply, communication with readers, other controllers in the system, the control programme and other devices (central alarm systems, barriers, etc.), as well as keep track of all data important for the system, including all permitted access types or failed unauthorised access attempts to buildings, spaces and data.

Populus access controllers  can also be successively connected to each other (RS485) into a communication line (up to 128 controllers can be connected in each line), at the end of which is a communication converter (Spider) via which such controller line is connected to the computer. The length of a single communication line (the distance between the first and the last controller) must not exceed 1,000 metres.

In special cases, access controllers can be equipped with an integrated TCP/IP converter and are therefore suitable for connection to the local network (TCP-IP). The integrated TCP/IP converter only supports communication of the controller in which it is installed. Additional controllers cannot be connected to this converter!