Texas Instruments 880 - Serial Interface Signals

Table 7-3. Serial Interface Signals
Pin
No. Source Signal RS232 CCITT
Function
PROTECTIVE GND
AA 101
Connected to earth ground.
2
P
TRANSMITTED DATA
BA 103
Conveys data to host.
3 H
RECEIVED DATA
BB 104
Conveys data to printer.
4 P REQUEST
TO SEND
CA
105
CNFG.CODE
14 or 15 ON: ON at
all times.
CNFG.CODE 13 ON: ON when
printer on
line;
OFF when printer is off line.
5 H *CLEAR TO SEND CB 106
CNFG.CODE 14 or 15 ON: Not
used.
CNFG.CODE 13 ON: Must be ON
to send data.
6
H
*DATA SET READY CC 107
Must be ON to send/receive data.
7
SIGNALGND AB 102
Ground reference for interface
signals.
8 H
*RECEIVED LINE CF
109
CNFG.CODE 140r 15 ON: Not
SIGNAL DETECTOR
used.
CNFG.CODE 13 ON: Must be on
to receive data.
9
P
+ VOLTS
+ 12 Vdc Input bias; tied to 1 K
series resistor.
10
P -VOLTS
-12 Vdc Input bias; tied to 1 K
series resistor.
11 P READY/BUSY
Signals READY/BUSY status to
host;
READY
ION when CNFG.CODE
13, 14, or 16 enabled;
READY /OFF when CNFG.CODE
15 enabled.
20
P
DATA TERMINAL
CD
108.2
CNFG.CODE
14 or 15 ON: ON all
READY
the time;
CNFG.CODE 13 ON: ON when on
line; OFF when off line.
Same as READY /BUSY when
CNFG.CODE8AON.
P = Printer
H
= Host
Pins
12-19and21-25are not used.
* Biased on
with no connection.
7-4