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5/ Technical Information
DB-25 Pin Connections Used
Pin
Name
Symbol
I/O
Function
2
Transmit Data
TD
0
DC output signal
3
Receive Data
RD
i
DC input signal
4
Request Data
RTS
0
ON: sends carrier
5
Clear To Send
CTS
i
ON: xmission enabled
6
Data Set Ready
DSR
i
ON: remote device ready
to receive data
7
Signal Ground
SG
-
Reference 0 voltage for
all signals
8
Data Carrier
DCD
i
ON: carrier present
Detect
20
Data Terminal
DTR
0
ON: local terminal ready
Ready
Notes:
Pins not depicted are not used.
All pins except pin 6 (DSR) and pin 8 (DCD)
are considered OFF if open.
Pin 6 (DSR) and
pin 8 (DCD) is considered ON if open.
If the
output signal from the DTR is connected to both
DCD and DSR, the output high/low voltages may
not be within specifications.
Dotted lines represent optional or alternate con-
nections.
Signal Bit Structure
A.
One start bit
B.
From 5 to 8 data bits
C.
If parity is in use, 1 parity bit
D.
1 or 2 stop bits
DB·25 Pin Connections
Local Unit
(PC-2)
Remote Unit
(peripheral)
A logical "high" signal
(+
voltage) is used to represent a
binary 1 bit.
A logical "low" (- voltage) is used to
represent a binary 0 bit.
Pin 2
Transmit Data
* > < *
Pin 3
Receive Data
*
*
Pin 4
Request to Send
* > < *
Pin 5
Clear to Send
*
*
Pin 6
Data Set Ready
*~
/ *
Pin 7
Signal Ground
*
*
Pin 8
Carrier Detect
*A*
Pin 20
Data Terminal Ready
*
---------~--------
*
50
51
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