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P/N 1070334 (ML) • REV A • ISS 04AUG14
In this case even a B-channel connection can be established.
Meanwhile, the polling mechanism repeats until the connection
has come about.
Priority switching
If the ATS7120/7121 ISDN dialler is used in a configuration
with other ISDN equipment on the same S0 bus, a fax or
telephone could occupy both B-channels when the
ATS7120/7121 ISDN needs to transmit an alarm event.
Standard ISDN methods will not allow a B-channel to be freed
for the ATS7120/7121 to use.
Consequently, the current state of the active sessions on the
local S0 bus are stored in an internal database. The
ATS7120/7121 ISDN "knows" if there are any B-channels
available and also keeps a record of the current session
parameters, such as TEI, call reference value, and the send
and receive sequence numbers.
When both B-channels are occupied, the ATS7120/7121 ISDN
sends a disconnect signal on behalf of one of the connected
ISDN devices. The ISDN network will perform further
necessary actions. The disconnect signal will be sent for the
other device if there is still no connection after five seconds. If
there is no B-channel available after another delay of five
seconds, the dialler sends a disconnect signal for both devices.
When still no B-channel is available, a timeout will occur. As
soon as there is a B-channel available, the dialler will transmit.
After the last timeout, the ATS7120/7121 ISDN physically
disconnects the S0 bus from the other terminal equipment by
its internal relay and waits one minute for the network to
stabilize. It should now be possible to make a call. When the
last call has succeeded, the relay switches back to connect all
other devices to the S0 bus again.
Installation
Mounting location
ATS7120/7121 must be mounted inside an ATS panel housing.
WARNING:
Electrocution hazard. To avoid personal injury or
death from electrocution, remove all sources of power and
allow stored energy to discharge before installing or removing
equipment.
Mounting the unit
Mounting ATS7120/7121 into an ATS2000/3000/4500
control panel
See Figure 1.
1. Place the clips in the square holes (item 4). Use metal
pillars when available.
2. Mount the ATS7120/7121 using screws.
3. Connect the ATS7120/7121.
Mounting the ATS7120/7121 into an ATS4000 control panel
See Figure 2.
1. Remove the screws (item 1) and lift off the control panel
PCB.
2. Place the extension pillars with the plastic rings on top of
the existing pillars (item 3).
3. Place the clips in the square holes (item 4).
4. Connect the ATS7120/7121.
5. Mount the ATS7120/7121 using the screws and extension
pillars (item 5).
6. Place the ATS control panel PCB back into its original
position and mount using screws.
Connecting the ATS7120/7121
1. Connect the flat cable (item 2) between the control panel
(connector J20) and the dialler (connector CONN1).
2. Connect the incoming ISDN line from the NT1 into
CONN3.
3. Connect the outgoing ISDN line to other ISDN devices into
CONN4.
4. Make 1 loop with the ISDN lines through the ferrite
(item 6).
Host power supply
The user must ensure that the power drawn by the
ATS7120/7121 ISDN, together with the host and any auxiliary
terminal equipment drawing power from the host is within the
rating of the host power supply.
MI address selection
ATS7120/7121 are addressable units, which can share the
panel bus (MI-bus) with other devices. The A0 jumper must be
placed on the two pins beside the RJ45 ISDN connections
(default) to have the correct address.
Connecting an ISDN terminal to the ATS7120/7121 ISDN
via the S0 out connector
It is possible to connect ISDN terminals to the ISDN line.
Connect all ISDN terminals to the outgoing S0 bus (CONN4).
If the ATS7120/7121 is the only ISDN device connected to the
NT1, then the ATS7120/7121 can terminate the S0 bus with
100 ohm resistors by placing the jumpers marked "TRM1 &
TRM2" on the RJ45 connector side of the jumpers. Never
place these jumpers, in case any other ISDN terminal is
connected to the outgoing ISDN connector (CONN4).
Caution:
Never connect telephones in parallel (using the
second RJ45 connector on the NT1) with the ATS7120/7121
ISDN!
For security reasons, it is recommended that
no
devices be
connected to the second RJ45 connector of the NT1. Proper
priority switching is not possible in case the second RJ45 is
used.
Advice should be sought from a
telecom telephone engineer
if
in any doubt regarding the connection of these terminals.
ATS7120/7121 overview
See Figure 5.
Figure 5 legend
Item
Description
1.
CONN1, connects to ATS control panel.
2.
CONN3, RJ45 connector. Incoming ISDN from NT1.