You are misreading what it says.
Set UART in receiver to 9600 baud one stop bit, no parity.
Read what it says in page you quote re levels.
When *BW is open or low, the board sends strings of 5 ASCII characters on the TX pin.
From what it says I ASSUME that it then pauses and then repeats.
If you have a board it would very very very very easy to look at the TX pin and see.
The 5 character ASCII string is equal to.
ASCII "R" = $52
ASCII Carriage return = $0d= 13_decimal
Digit1 Digit2 Digit 3 gives3 ASCII coded digits 0-9 to give values 000 to 255 max. Order MAY be reversed (LSD first).
Sending this to a PC using a terminal program would display for eg a ramp that happened to ramp at one count per string.