Comtrol WCom2 - Manual (Page 29)

Port Monitor and Test Terminal User Guide: 2000485 Rev. B Using Test Terminal - 29
Sending and Receiving Data (RS-485: 2-Wire)
7. Right-click and remove the check mark on the Receiving COM port.
Neither COM port is sending or receiving data but shows Ready on the Status
bar.
8. Reverse the sending/receiving windows one at a time. Set the Receive option
first, then in the opposite window, select the Send option.
The Status line shows Sending or Receiving in the reverse windows.
Data is now scrolling in the COM40 window. COM41 is static as it is not receiving
data but transmitting data.