Pins 2 and 14 onthe DB 25 go to the relay key engager on the Motorola.Into the 4wiremodule, take a standard CAT5 cable and use the BLUE pair (Solid is + andstriped is -) to connect audio into the module…from the radio and the Greenpair (striped is + and solid is -) for audio from the module…into the radio.
Helixnet RJ45  4wire pin out :

Pin 1 RS-422 Data TX+Pin 2 RS-422 Data TX-
Pin 3 Audio Send+
Pin 4 Audio Receive+
Pin 5 Audio Receive-
Pin 6 Audio Send-
Pin 7 RS-422 Data RX+
Pin 8 RS-422 Data RX-

Once that is allset, go to the HMS menu, go to CONTROL I/O , then OUTPUT, then RELAY 1 andselect which button on the HMS you want to use to key the radio.  If, you want to have a channel that ALWAYStalks to the radio, make that key non-latchable (in the menu, go to STATIONSETTINGS, KEYSETS, pick the KEYSET# and select NON-LATCHING)…or you could setit to the CALL button for that keyset, and to key the radio on that channel(occasionally), press the CALL and TALK at the same time.  This way, you can choose when you want totalk to the channel and when you want to talk to that channel PLUS the radio.