Adding a COM4 You can add one COM4 to KSU1 and one COM4 to the KSU2. These modules expand the DX-80 system CO line interface capacity to a maximum of eight CO line ports in each KSU (16 total CO line ports when used in KSU 1 & 2). When adding a COM4 to either KSU, connect to the 408M/E via the COM4 module ribbon cable. This ribbon cable has the logical system address of SLOT 5 in both cabinet 1 (KSU1-408M) and cabinet 2 (KSU2-408E). COM4 modules are installed using four 1.5 cm brass-color standoffs. Always install the COM4 module beneath the CPM module (in KSU1) by first removing the CPM, installing the COM4, and then re-installing the CPM. This is required whenever you install the InSkin Voice Processor.