Omron F250-UME Software Manual page 851

Normal Serial Interface
6-2 Normal Serial Interface
Note RS-232C/RS-422 and Ethernet connections cannot be used at the same time.
This section explains how to set the required communications specifications
and the I/O format for using the Controller's serial interface (with a RS-232C/
RS-422 connection or Ethernet connection) to communicate with an external
device, such as a personal computer.
Controller
Use only one of these type of connections for the serial interface.
Command
input
Processing
result output
Personal computer
Section 6-2
6-2-(1)