4.0 INSTALLATION
The Model 1226 is designed to be easy to use. After configuring
the DIP switches, connect the two twisted pairs using one of three
methods: RJ-11 jack, RJ-45 jack or terminal blocks. Figure 3 shows
the location of the RJ-11 jack, RJ-45 jack or terminal blocks, as well as
the female DB-25 connector, on the rear of the Model 1226.
The Model 1226 operates over 4-wire twisted pair. The two pair
must be 26 AWG or larger “dry”, unconditioned, metallic wire. Dial-up
analog circuits, such as those used with a standard Hayes type
modem, are not acceptable. The twisted pair may be shielded or
unshielded. Both types yield favorable results. You will need a pair of
Model 1226s for each circuit—one at each end of the circuit.
4.1 TWISTED PAIR CONNECTION USING RJ-11 OR RJ-45
The RJ-11 and RJ-45 connectors on the Model 1226’s twisted pair
interface are pre-wired for a standard TELCO wiring environment. The
signal/pin relationships are shown on the following table:
RJ-11
SIGNAL
RJ-45
SIGNAL
1 ---------GND
1---------------NC
2 ---------RCV-
2---------------GND
3 ---------XMT+
3---------------RCV-
4 ---------XMT-
4---------------XMT+
5 ---------RCV+
5---------------XMT-
6 ---------GND
6---------------RCV+
7---------------GND
8---------------NC
When connecting two Model 1226s, it is necessary to use a “cross-
over” cable. The diagram below shows how a crossover cable should
be constructed for an environment where both Model 1226s use a
4-wire RJ-11 or RJ-45 connector (RJ-45 is shown below). Similar logic
should be followed when using RJ-11 connectors or a combination of
the two.
SIGNAL
PIN#
PIN#
SIGNAL
GND
‡
2
7---------------------GND
‡
RCV-
3
5---------------------XMT-
XMT+
4
6---------------------RCV+
XMT-
5
3---------------------RCV-
RCV+
6
4---------------------XMT+
GND
‡
7
2---------------------GND
‡
†
Standard color codes—yours may be different
‡
Connection to ground is optional
Figure 4. AT&T Standard Pin Assignements
4.2 FOUR-WIRE CABLE CONNECTION VIA TERMINAL BLOCKS
If you are not going to use the modular jacks, then follow the
instructions below.
A.
Locate the terminal block on the back of the unit. It should look like
the following diagram:
B.
Connect one pair of wires to XMT+ and XMT- (transmit positive
and transmit negative) on the terminal block, making careful note
of which color is positive and which color is negative.
7
8
1 - Blue
2 - Orange
3 - Black
4 - Red
5 - Green
6 - Yellow
7 - Brown
8 - Slate
1 - Blue
2 - Yellow
3 - Green
4 - Red
5 - Black
6 - White
RX+ RX- GND TX- TX+
Powered Short Range
Modem
Made In The USA
LINE
Parallel Interface
Power
RX+
RX-
GND
TX-
TX+
Figure 3. Rear view of the Model 1226
