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Stop Bits
Parity
RTS/DTR Line Driver Inactivity State
DTR Line Driver Inactive State is: High
High ? (Y/N, CR for no change):
RTS Line Driver Inactive State is: High
High ? (Y/N, CR for no change):
Select 7), from the Serial Port Configuration
Menu
changes the DTR driver state,
Default is
“High”
Select 6), from the Serial Port Configuration
Menu
changes the RTS driver state,
Default is
“High”
Select parity:
1 For None
2 For Even
3 For Odd
Enter Request :
Select 5),
from the Serial Port Configuration Menu
selects the
Parity,
Default is None
Select stop bits:
1 For 1
2 For 1.5
3 For 2
Enter Request :
Select 4), from the Serial Port Configuration Menu
changes the
Stop Bits,
Default is 1
Type
“Y”
for YES or
“N”
for NO and press ‘Enter’.
The Stop Bits are used to signal the end of communication for a single packet. Since the data is
clocked across the lines and each device has its own clock, it is possible for the two devices to
become slightly out of sync. Therefore, the stop bits not only indicate the end of transmission but
also give the computers some room for error in the clock speeds. The more bits that are used for
stop bits, the greater the lenience in synchronizing the different clocks, but the slower the data
transmission rate.
Parity is a simple form of error checking used in serial communication. For even and odd parity, the
serial port will set the parity bit (the last bit after the data bits) to a value to ensure that the
transmission has an even or odd number of logic high bits. For example, if the data was 011, then for
even parity, the parity bit would be 0 to keep the number of logic high bits even. If the parity was odd,
then the parity bit would be 1, resulting in 3 logic high bits. This allows the receiving device to know
the state of a bit so as to enable the device to determine if noise is corrupting the data or if the
transmitting and receiving devices' clocks are out of sync.
With no parity selected, it's assumed that there are other forms of checking that will detect any errors
in transmission. No parity also usually means that the parity bit can be used for data, speeding up
transmission. In modem-to-modem communication, the type of parity is coordinated by the sending
and receiving modems before the transmission takes place.
RTS (Request to Send)/ DTR (Data Terminal Ready) is normally used in conjunction with an external
modem. With no modem the RTS and DTS
default state is High.
