Arduino RS232 commands to CAVRO Pump

I am trying to use my arduino to control TECAN Cavro Syringe pump. I am unable to establish communication between arduino and the pump. I am able to establish communication between arduino & termite and the Pump & termite.

Materials being used are
Keyestudio Arduino Mega
Keyestudio TTL to RS232 Converter
Cavro Syringe Pump
Wires/connectors

I have attached the pump manual and schematic. Let me know your thoughts