Connection reference

Serial connection parameters

Match both ends of the link and keep terminal newline behavior explicit.

Reviewed: 2026-08-01 Applies to: Serial Port Utility 6.6.x

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Connection and serial parameters

Serial communication only works when both sides agree on the same link settings.

Port: the COM port assigned by the operating system. Re-plugging a device can change it.
Baud rate: must match the target device. Common values include 9600, 115200, 460800 and 921600.
Data bits: usually 8.
Stop bits: usually 1.
Parity: usually None, but industrial devices may use Even or Odd.
Flow control: keep it disabled unless the device documentation explicitly requires RTS/CTS or XON/XOFF.
Append Line Ending: when you use Send, Ctrl+Enter or loop send, the selected CR, LF, CRLF or LFCR bytes are appended to the complete outgoing message.
Enter Sends: when the receive terminal has focus, pressing Enter immediately sends the selected CR, LF, CRLF or LFCR bytes. It does not change messages sent from the lower send editor.

Custom baud rates are available, but stable high-speed communication still depends on the serial chip, driver, cable quality and target firmware.