Installation ProceduresApollo CNX80 Installation Manual 560-0982-00 Rev D 2-312.8.9.3 VOR Flip-Flop SwitchP1-34 VOR Flip Flop InThe VOR Flip Flop In is used to toggle the active and standby VOR/LOC frequencies. A momentaryground on this input performs the same function as pressing the VOR flip-flop soft key (↔) on the bezel.2.8.9.4 Push to Talk (PTT)P4-4 PTTThe PTT is used to transmit on the COM radio. A ground on this input enables the Com MIC audio andcauses the Com transceiver to transmit on the active frequency.2.8.9.5 Com User List SwitchP1-15 UP Discrete InP1-33 DOWN Discrete InThe Com User List inputs are momentary, active-low discrete inputs and are used to display the Com UserList and select a frequency. When not displayed, a momentary grounding on either of these inputs causesthe Com User List window to be displayed. When the Com User List window is displayed, a momentaryground on the UP Discrete In (P1-15) causes the highlighted frequency to move up to the next frequency inthe list. A momentary ground on the DOWN Discrete In (P1-33) causes the highlighted frequency to movedown to the next frequency in the list. Once selected, the frequency can be made active by pressing the ComFlip-Flop button.2.8.9.6 Suspend SwitchP5-76 Suspend InThe Suspend In input suspends automatic sequencing of waypoints in the active flight plan. A momentaryground on this input performs the same function as pressing the SUSP key on the CNX80 bezel.2.8.9.7 Audio Inhibit InP5-76 Audio Inhibit InThe Audio Inhibit In is used to inhibit the CNX80 audio messages. A ground on this input causes CNX80audio messages not to be played; if this input is open CNX80 audio messages will be played. Any audiomessages that are inhibited because of this input will not be played when the audio inhibit condition isremoved.NOTEThe Audio Inhibit input will not inhibit the momentary tone that is played by the CNX80whenever a status message is available. This tone can be disabled by the user via thesystem configuration page.