Explanation of Access Controller Pro 2 connections needed

Hi,Can some explain the individual connections of the terminal block and which ones I should be using?I need to connect to my gate opener control board which has:COM - commonOPEN - to open gateIf these are bridged, then the gate opens.I was expecting the ACP2 to have 2 relay connectionsCOM - commonNO - normally openWhich would connect directly to my control boardCOM to COMNO to OPENThe ACP2 terminal block has 8 connections:Ext:+5vPort A:D1D0GNDPort B:REL1REL2Power:PS1PS2Which ones should I connect up to where?Thanks in advanceDave