Flexy202 failing to communicate over serial

My Flexy202 is failing to establish communication with a slave device on serial. I tested the same device on flexy 202 and 203 and its communicating perfectly fine. I suspect i am missing something on configuring the serial communication of builtin serial port of the flexy 202. Its giving this error in the logs "
smbs-Serial port not opened". Please assist thanks in advance.

Make sure you have configured the serial port for the correct protocol:

ok thanks let me try that.