... connection and grounding• Wire-wrap pins to monitor alarm relay activity (46 total, 23 per HMU)• OSP hardened with an operational temperature range -40° C to +65° C• 19-inch or 23-inch rack mount ... mechanics shelves• DB-25 and DB-9 connectors for connection to a computer, terminal, modem, or ThinMux (M13)• 10BaseT (RJ-45) and 10Base2 (BNC) LAN connectors for remote network management• Screw-type ... can manage up to 28 line units each. Up to 56 HiGain line units (two 3192, two DDM+, or four 220-type shelves) can be managed when both slots of the HRM-238 shelf are populated. Up to 32 HMU-319...