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Number of "1"s
in
character
Parity
Specified
Parity
Bit
Model DRC-91C/93C
Model
8223
Rs-232C Interface
M O D E L 8 2 2 3 R S - 2 3 2 C I N T E R F A C E
8223.1 INTRODUCTION
number of
1
bits in the character.
This Section contains information
Refer to Table 8223-1 for parity
pertaining
to
the
Model
8223
determination.
RS-232C
Interface
for
the DRC-
91C/93C
Temperature
Controller.
Table
8223-1.
Parity Determina tion
Included
is
a
description,
specifications,
installation,
o p e r a t i o n
and
maintenance
information.
8223.2
DESCRIPTION
The
8223
RS-232C
Interface
is
designed to be installed in a DRC-
91C/93C and provide an interface
with an external Rs-232C instrument
The Model
8223
RS-232C Interface
such as a computer, modem or
CRT.
has a
25
pin D style connector
The interface operates in a half
located on the rear panel.
Pin
duplex
m o d e
(it can only transmit
Assignments
are
shown
in
Table
and
receive
information
in
one
8223-2.
direction
at
a
time) and
data
transmission is asynchronous (each
Table
8223-2.
Connector Pin
character is bracketed by start and
stop
bits
that
separate
and
synchronize the transmission and
receipt of data).
The baud rate is
switch selectable at
300
or
1200
baud and the interface maintains
EIA
voltage
levels
for
data
transmission.
Figure
8223-2
gives a transmission
format which shows the data bits
framed
by
the
start
and
stop
synchronization bits.
The data is
transmitted
using
two
voltage
levels which
represent
the two
binary states of the digit. A logic
The Rs-232C signals are used in the
0
(or SPACE) is
+3
to
+12
VDC.
A
following manner:
logic 1 (or MARK) is
-3
to
-5
VDC.
When data is not being transmitted,
Protective Ground
(AA)
-
conductor
the line is held low (MARK state).
is taken to case ground potential
When the transmission device is
and
is
common with
the
signal
ready to send data, it takes the
ground (AB)
.
line to the high (SPACE) state for
the
time
of
one
bit.
This
Transmitted Data (BA)
-
transmits
transition is called the start bit.
data using the
EIA
voltage levels
The
remaining
data
is
then
(+12V and -5V).
transmitted.
If a parity bit is
used,
it follows the character.
Received Data (BB)
-
accepts data
The parity bit is determined by the
Assignments for
RS-232C
using EIA voltage levels.
COPYRIGHT
12/87
ISCI
8223-1
Pin
1
2
3
4
5
6
7
8
20
Odd
Even
Odd
Even
Odd
Odd
Even
Even
0
1
1
0
Description
Signal
Protective Ground
Transmitted Data
Received Data
Request to Send
Clear to Send
Data Set Ready
Signal Ground
Rcvd Ln Sgnl Dtctr
Data Terminal Rdy
AA
BA
BB
CA
CB
cc
AB
CF
CD
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