Asynchronous Terminals and Printer Processes Programming Manual

PRINTER PROGRAMMING CONSIDERATIONS
Cabling Recommendations
When connecting DTR printers to the host through modems, use the
following pin-to-pin connections:
HOST MODEM
FG 1 ---------------------------- 1
TXD 2 >--------------------------> 2
RTS 4 >--------------------------> 4
CTS 5 <--------------------------< 5
DSR 6 <--------------------------< 6
SG 7 ---------------------------- 7
DCD 8 <--------------------------< 8
DTR 20 >--------------------------> 20
/------< 3 RXD \
RXD 3 <-------------------+ OR *
\------< 16 SRC /
* Use pin 16 if the modem has a low-speed, reverse-channel
option. Otherwise, use pin 3 for the full-duplex modem.
MODEM PRINTER
FG 1 ---------------------------- 1
RXD 3 >--------------------------> 3
RTS 4 <--------------------------< 4
CTS 5 >--------------------------> 5 *
DSR 6 >--------------------------> 6 *
SG 7 ---------------------------- 7
DCD 8 >--------------------------> 8 *
DTR 20 <--------------------------< 20
SCA 19 <--------------------------< 19
TXD 2 <------------------\ ____
OR +------< 2 (Busy/Busy)
STD 14 <------------------/
* The printer might or might not monitor these signals.
____
If the DTR signal (Busy/Busy) from the printer is transmitted
through TXD (pin 2), then RTS (pin 4) must be on. If the DTR
signal (Busy/Busy) from the printer is transmitted through STD
(pin 14), SCA (pin 19) must be on.
November 1987 7-25