Radio Shack 26-1145 - Page 16

BAUD
RATE
S6
S7
S8
110
Closed
Closed
Closed
150
Closed
Closed
Open
300
Open
Closed
Closed
600
Open
Closed
Open
1200
Closed
Open
Closed
2400
Closed
Open
Open
4800
Open
Open
Closed
9600
Open
Open
Open
PARITY
ENABLE
S4
STOP
BITS
S5
Parity
Enable
Parity
Disabled
Closed
Open
One Stop
Bit
Two
Stop Bits
Closed
Open
WORD
LENGTH
S2
S3
(Excluding
parity
bit)
5
Bit Word
Closed
Closed
6 Bit
Word
Closed
Open
7 Bit
Word
Open
Closed
8 Bit
Word
Open
Open
PARITY
SELECT
Odd Parity
Even
Parity
SI
Closed
Open
TABLE
3. OPERATION
OF
SENSE
SWITCHES
Logic
Conventions
The
logic internal to the RS-232-C
operates with TTL
logic levels
(3.5V or more
=
Logic
1
, and
0.8V
or less
=
Logic
0).
The logic
convention used
for interfacing two RS-232-C devices
is
ElA
levels
(—3V
or less
=
Logic
one,
+3V
or more
=
Logic
0).
The logic
levels must
therefore be converted
from one
convention
to the
other
when
interfacing
two devices.
The blocks
in
Figure
4
labeled
EIA
To TTL
and
TTL
To
E1A
provide this level conversion.
13