This wiring solution can be used when a customer needs to connect a Motorola radio with an M9 (8 Pin) accessory connector to a FreeSpeak II Base II using the 4-wire audio port and GPIO relay for PTT.

Key finding: The Motorola M9 accessory connector was verified so that Pin 5 and Pin 8 correspond to the radio PTT button pair. For this wiring solution, Pin 8 should be used as the preferred PTT return.

Tested setup

Clear-Com device: FreeSpeak II Base II
Radio accessory: Motorola M9 connector
FSII Base II 4-wire port: RJ45
FSII Base II GPIO port: DB-15
GPO used: GPO1
GPO triggering event: Channel 3 / Call

Validated pinout

Pinout - Motorola M9 (8 pin) accessory to FSII 4-Wire (RJ45) and GPIO (DB-15)

Motorola M9 Pin	Motorola Signal	FSII Base II Connector	FSII Pin	FSII Signal

Motorola M9 Pin	Motorola Signal	FSII Base II Connector	FSII Pin	FSII Signal
Pin 2	Speaker +	RJ45 4-wire	Pin 4	Audio In +
Pin 3	Speaker -	RJ45 4-wire	Pin 5	Audio In -
Pin 6	Mic +	RJ45 4-wire	Pin 3	Audio Out +
Pin 7	Mic -	RJ45 4-wire	Pin 6	Audio Out -
Pin 5	PTT	DB-15 GPIO	Pin 1	Relay 1 COM
Pin 8	PTT return	DB-15 GPIO	Pin 3	Relay 1 NO

FSII Base II GPO configuration

Set the 4-Wire Port Function to “to Matrix”
Configure GPO1 so that it triggers from Channel 3 (Key Target)/ Call (Behaviour).
When the assigned Call event is activated, the relay closes across the Motorola PTT pair and keys the radio.

Recommended wiring rule: Relay follows the PTT button pair. Audio follows the audio pair.

How PTT works

The FSII Base II relay should be wired as a dry contact across the same two Motorola pins used by the radio's physical PTT button. In this solution, that pair is M9 Pin 5 and M9 Pin 8.

Use Relay 1 COM and Relay 1 NO so the contact is open when idle and only closes when the configured GPO is triggered.

Important wiring notes

Use the FSII Base II relay as a dry contact only.
Do not inject voltage into the PTT line.
Use Relay COM and NO across the same two pins that activate the radio's physical PTT button.
Do not use NC for normal PTT triggering because NC is closed when idle and may keep the radio keyed.
Keep balanced audio pairs together.
Do not tie Audio In-, Audio Out-, Mic-, or Speaker- to ground unless the radio accessory wiring specifically requires it.

Caution: If COM and NC are used instead of COM and NO, the radio may remain keyed while idle.

Verification steps

Confirm the Motorola connector and pinout.
Connect FSII Base II Relay COM and NO to the Motorola PTT pair. [ DB-15 into base GPIO]
Set FSII Base II GPO1 to trigger from Channel 3 / Call.
Press Call and confirm the radio keys up. [Radio LET lit up -Red]
Connect the audio. [RJ45 to base 4-wire port - e.g Port 3]
Test audio both ways.
Adjust levels if needed. [4-Wire Port Input/Output Gain adjustment in CCM]

Radio keys continuously: Check that the relay is wired to COM and NO, not NC. PTT does not trigger: Confirm GPO1 is assigned to Channel 3 / Call and verify continuity across the Motorola PTT pair. Audio missing or distorted: Recheck polarity on the balanced audio pairs and confirm the negative audio lines have not been incorrectly tied to ground.