...
In a new presentation, under Layout > Zones, select Add Zone.
Resize the zone and , give it a name (in the image below, we’ve named the zone for example, "Event Handler"), and under Type, select Audio.
Switch to the Content tab and toggle the Interactive switch to on.
Go to Widgets and drag and drop the Event Handler widget into the playlist area.
Under Events, click select the UDP event to activate it, and then click on select the Event Handler state to attach it, as shown in the image below
In Event Properties > Specify UDP Input enter the UDP input that the player will be listening for (for example, “AMX_Command1").
With the state selected (notice that Event Properties turns to State Properties), select Add Command inthe Advanced tab.
Select the type of serial command to send (Serial-send string with EOL, Serial-send string without EOL, or Serial send byte) once the UDP input message is received.
Enter the serial command string/value.
Configure the serial port setting by navigating to Presentation Settings > Interactive > Connectors. The serial settings from this panel must match the serial settings of the device you would like the player to communicate with (i.e. Baud rate, Data bits, Parity, Stop bits, Protocol, Send EOL, Receive EOL). The 3.5mm serial connector on the player is referred to as "Port 0".
Go to Presentation Settings > Interactive > Networking and ensure the UDP Destination Port and UDP Receiver Port are set to the same value as your UDP controller (the AMX controller in these images).
...