Samsung TV C4 Control over Serial

[Dueport]

In our kitchen, we have a Samsung UN24H4500AF - the C4 driver says it will work over IR or serial.  We got it working over IR but I'm trying to get rid of the IR flasher and use the serial control but I can't seem to get it to work.  It has been setup properly on the C4 programming side so I think the issue is on the TV side.  I've connected the 3.5mm cable with a 4 terminal jack (should support the 3 terminals the serial needs) into the Ez-Link jack on the back of the TV (this is the Samsung serial port).  My understanding is that serial control needs to be activated through the secret Samsung service menu - accessible by, with the TV off, pressing on the remote: "mute" -> "1" -> "8" -> "2" -> "power".  Once in the service menu I select "control" -> "sub option".  There I see "RS-232 jack" has 3 options "UART" (which is the default); "Logic", "FANET", and "debug".  Selecting any of these does not seem to do the trick.  The only other seemingly related option under the "sub option" menu is "UART ENABLE".  I've tried toggling that on and off with "UART" also selected under the "RS-232 Jack" option and I still don't get anywhere.  Does anyone have experience enabling RS-232 C4 control on Samsung TVs?  

[Dueport]

Looks like the driver instructions say to use "URT" so my issue may be improper pinout - will pursue that and update

[Dueport]

That was it - it requires a null modem wiring configuration and I'd wired it for audio/IR - swapped two wires at one end and off to the races!