You'll need to create a custom Cat5e patch cable going from the CAB-PHD4XS2-SPLIT to the codec's RJ45 to D-SUB camera control cable. Or create a custom RJ45 to D-SUB camera control cable if you prefer to connect it straight to the codec. Refer to the PrecisionHD Camera User Guide. Check the RJ45 pin-outs on pg 20 for the CAB-PHD4XS2-SPLIT and on pg 17 for the codec camera control port.
The CAB-PHD4XS2-SPLIT uses pins 7 and 3 for RS232 TX/RX.
The codec's camera control cable if you wish to use a Cat5e patch cable, it uses pins 6 and 3 for RS232 TX/RX.
The codec's camera control port is you wish to go straight from the Y-cable to the codec, it uses pins 2 and 3 for RS232 TX/RX.