Used in conjunction with the ACTAtek3 unit, the External I/O board provides an additional layer of security for access control systems when the ACTAtek3 terminals are exposed to general access.  An encrypted serial link from the ACTAtek3 unit connected to the External I/O board ensures the door release  mechanism cannot be operated directly. This means that even when there is a vandal attack or someone removes the ACTAtek3 terminal by force, the External I/O board Secure Relay will maintain operation and keep the door mechanism locked against unauthorized access.