Operation
3-7
1558A APS
dition occurs if there are no pulses for 175 or more bit times.
The loss of signal state will be cleared when one or more
data pulses are detected on the receive path. After the pulses
are detected, the LOS LED indicator will be turned OFF.
3.4
Rear Panel Connections
All APS unit wiring connections and option switches are
located on the rear panel of the 1558A unit. The function
and description of these items are discussed in the following
paragraphs (refer to Figure 3-3 and the 1558A Configura-
tion Guide at the end of this manual).
3.4.1
COM Bus Connections
The two 6-pin modular connectors labeled COM BUS IN
and COM BUS OUT on the rear panel may be used to con-
nect to the optional 1559 APSM site manager. These ports
are wired to allow daisy chaining one or more units off of
the APSM (the OUT port is connected to the IN port from
unit to unit). The COM BUS IN and OUT connectors are
physically RJ11, 6-pin modular jacks. The function of the 6
pins are described in the table below. For additional infor-
mation concerning the site manager, consult the TxPORT
1559 manual.
3.4.2
Network T1 Connections
The NET A and the NET B T1 modular jacks are used to
connect the 1558A to the T1 facilities using RJ48 modular
cables. Physically, the 1558A NET A and NET B connec-
tors are RJ48, 8-pin modular connector. The usage of each
of the eight pins found in the connector are described in the
table below. The 1558A unit comes with three ten foot RJ48
cables (NET A, NET B, and DTE).
3.4.3
DTE T1 Connection
The DTE T1 modular jack is used to connect the 1558A to
the customer premise equipment using a RJ48 modular
cable. Physically, the DTE connector is RJ 48, 8 -pin modu-
lar connector. The DTE T1 port is not designed connect
directly to a TELCO T1 facility. The 1558A unit comes with
three ten foot RJ48 cables (NET A, NET B, and DTE).The
usage of each of the eight pins found in the connector are
described in the following table.
3.4.4
Screw Terminal Connections
Several screw terminals are provided at the rear of the unit
for connecting external power and alarm wiring. All connec-
tions to these terminals strip should be made using 26-
gauge wire, or larger. The purpose of these terminals is
briefly described as follows:
Ground: This terminal is used to connect the chassis
ground to an external earth ground.
PIN
COM BUS IN
COM BUS OUT
1
Not Used
Not Used
2
Signal Ground
Signal Ground
3
Data, output
Data, Output
4
Data, input
Not Used
5
Signal Ground
Signal Ground
6
Not Used
Not Used
PIN
NET A
NET B
1
Data In, Tip
Data In, Tip
2
Data In, Ring
Data In, Ring
3,6
Not Used
Not Used
4
Data Out, Tip
Data Out, Tip
5
Data Out, Ring Data Out, Ring
7,8
Not Used
Not Used
PIN
DTE
1
Data In, Tip
2
Data In, Ring
3,6
Not Used
4
Data Out, Tip
5
Data Out, Ring
7,8
Not Used
-20 to -56 VDC, 200 MA
S1
DTE
COM BUS
NET B
NET A
IN
OUT
GND
–
V
DC (
A
)
RT
N
(
A
)
–
V
DC (
B
)
RT
N
(
B
)
Alarm
NO
C
o
mmo
n
Alarm
NC
S2
S3
S4
Figure 3-3
1558A Rear View
