User`s guide

12
Terminal To Modem (or DeE Host)
Refer to the diagram below to understand why a nun modem adapter may be needed when connecting the AUX
serial port to a modem or a DCE host. The EIA port will connect directly without a nun modem since it is a DTE
device.
Host
Modem
L··········
Transmit pmz _
Receive
~ln3 ~i~~ Transmit
pln2~ Receive
1·--'~~01
I~=.;-;C I
liiil
I ,oo_-J ~ ... RJ'S connec'2'
Modem
D i I
(-~ ~~
l ~'J
c; il
~ __ .. DCE __
E !::
mna
Receive "'C
pin3
/-------.. Receive
Transmit~
Transmit
pin 4 pin 4
DTR'
-J> DTR
pin 1
DSR--
DSR
Terminal To Host (DTE) OR Printer
Refer to the diagram below to understand why a null modem adapter may be needed when connecting the EIA
serial port to a serial printer or a host port without a modem (most hosts and serial printers are DTE devices).
The AUX port will connect directly without a nun modem since it is a DCE device.
• - EIA-
I' ~~I-··
~'
oTE
pin2
Transmit -- --
Host
l.
O
ii-I
'.
, i'
T '
E :
pin2
//- Transmit
Serial
Printer
f==;
pm S
Receive ...
pin20
oTR
pm S
...Receive
yin20
0 TR
DSR ~.n6
Serial
Printer
oCE
~=~
pin 3 pin 5
Receive -<II:
- Transmit
pin 5
pin 3
Transmit
--
~ Receive
pin 4
pin 1
oTR'
OTR
pin 4
pin 1
.oSR
oSR
--