Need help regarding Digi PortServer TS4

Hi all,
I have some problem regarding my PortServer TS4.

i want to connect my PC through UTP cross over cable to PortServer TS4 and and Serial port connected to my other Equipment System called Normac Air Systems.

so can any 1 please help me what kind of protocol i have to be use to configure the PortServer TS4, i already configured PortSerer as Serial bridging and all other profiles but i am not getting the response from the my equipment (Normak Air systems)

i have attached the drawing also so any 1 can understand easily.