Hardware handshaking uses additionallines ( DSR, D'IR, RTS, CTS) to signal when the
device is ready to receive data. These handshake lines use +3 to +25
Vdc
to indicate a
true, and -3 to -25 to indicate a false condition.
When
a
DTE
is ready to communicate,
it
drives the
DTR
line true.
The
DCE
(395) will respond by driving the
DSR
line true.
Then the
DTE
will drive RTS true when it is ready to receive data and the
DCE
will drive
CTS true when
it
is ready
to
receive data.
Table 2-2a. Model395 RS-232 Connections (08-9)
Pin Narne Direction Description
1
DCD
OUT
Carrier Detect
2 RxD
IN
Receive Data
3
TxD
OUT
Transmit
Data
4
DTR
IN
Data
Terminal Ready
5
GND
COMMON
Signal Ground
6
DSR
OUT
Data
Set Ready
7 RTS
IN
Request
To
Send
8 CTS
OUT
Clear
To
Send
9
NC
No
Connection
Table 2-2b. Standard
OTE
RS-232 Connections
Pin
08-9
1
2
3
4
5
6
7
8
9
08-25
8
3
2
20
7
6
4
5
22
\\Jarne
DCD
RxD
TxO
OTR
GND
OSR
RTS
CTS
RI
Direction
IN
IN
OUT
OUT
COMMON
IN
OUT
IN
IN
Description
Carrier Detect
Receive Data
Transmit
Data
Data
Terminal Ready
Signal Ground
Data
Set
Ready
Request
To
Send
Clear
To
Send
Indicator
The
Model395
RS-232
signal names
are
defined
below. A positive
voltage
above
+3Vdc is defined as a logic
'0'
or
'ON'.
A negative voltage below -3 Vdc is defined as
a logic
T
or
'OFF'.
OCD Intemally connected to pins 4 (DTR) and 6 (OSR)
in
the
model395.
A logic
'0'
signifiesthat
the 395 is ready for communication. See notes for
DTR.
TxD
SeriaI data output from
Madel
395.
RxD
SeriaI data input
ta
Madel
395.
DTR
Signal from a
OTE
that indicates
it
is ready for communication. This signal is
intemally connected to pins 1 (DCO)
and
6 (DSR). Upon receipt
of
a logic
'0',
the
DCD
and
OSR
are driven to logic
'0'
thus signaling that the 395 is ready for
communication.
GND
Connected to internal signal ground. This should
be
connected to a groundpoint
on
the device
that
the
395
is
going to cornmunicate with
for
proper
error
free
operation.
Initial Preparation 2-9
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