When I connect system serial port COM1 to RS-422/485 devices, why it cannot work and no communication?
The system BIOS default for serial port is RS-232, if user needs to connect RS-422/485 device that have to into BIOS to change port setting.
a. BIOS => Advanced => F81866 Super IO Configuration => Serial Port 0 Configuration => RS-232/422/485 mode selcet => [RS-422/485]
b. Open chasses and chnage jumpers select (SCT1/SCT2) for COM1 protocol setting.