PLC and Arduino communication using socket programming

Currently I am working with an industrial PLC which supports TCP/IP protocol. I am using my Audrino UNO and an Ethernet shield to read and write data to PLC using this protocol. I do not want to use modbus to achieve this.
Is there anyone in the forum who could help me on socket programming.

if you do an internet search for Arduino Ethernet you will find plenty of links to libraries and example code, e.g.

with the Arduino you can set up a TCP connection or send UDP datagrams
are the TCP/IP facilities on the PLC fixed (e.g. accepts UDP datagrams on a fixed port) or can you program it?