https://www.pulse-eight.com/p/195/opto-coupling-ir-cable-mono-stereo
1) Opto cable - (White Mono End) Connect to Control 4 - IR port
2) Black end which is Stereo connected to the - Input on the matrix- Port
3) IR emitter plugin into (Tx) On the Receiver
(IR Emitter) 
(TX Port on the right side)
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This is an EA Control ( See the diagram on where is the IR port for the Control 4)
(L) IR 3.5 mm jacks for up to eight IR emitters or for
a combination of IR emitters and serial devices. Ports 1 and 2 can
be configured independently for serial control or for IR control. See“Setting up IR emitters”
Attention :
Always use an Opto Mono-Stereo cable to connect control 4 with our Pulse eight matrix. And also the Opto Mono-Stereo cable must be the Pulse eight brand. This is to avoid any circuit or burn the IR board.
Thank you!