Installation Control Unit IV Reference Manual
2-12 529-0004 Ver.3
2.7.5 Connecting a master unit to a backup unit
To connect a master unit to a backup unit, you must use the redundancy kit (see Figure 2-4),
which includes a redundancy cable, a three-way ribbon cable and a synchronization cable.
For cabling, follow this procedure and refer to the connection diagram (see Figure 2-6).
1. Connect the master end of the redundancy cable to the
BACKUP
input on the master unit.
This connection ensures that the Control Unit that has the end labeled
MASTER
is the
master unit at startup. Connect the other end to the
BACKUP
input on the backup unit.
2. Connect one end of the synchronization cable to the COM 2 port on the master unit and
connect the other end to the COM 2 port on the backup unit (see Figure 2-6). In a
redundancy system, COM 2 takes on its preset values (see Chapter 3).
3. To connect a host computer to the COM 1 port on the Control Unit, use the three-way
ribbon cable. Connect the male DB-25 connectors to COM 1 on both Control Units, then
connect the female connector to a computer, a modem or an Ethernet-RS-232 bridge as
follows:
• To connect the host computer using a direct link, connect the male end of a round
RS-232 cable (DB-25) to the female connector on the three-way ribbon cable.
Connect the female end of the round RS-232 cable to the computer’s communication
port.
• To connect the host computer using a remote link, see section 2.7.1 for modem
connection instructions.
• To connect a host computer to the Control Unit using a LAN connection, connect the
male end of a round RS-232 cable (DB-25) to the female connector on the three-way
ribbon cable. Connect the female end of the round RS-232 cable to an external
Ethernet–RS-232 bridge.
4. If you have not yet connected the Control Unit’s test ports, run a short coaxial cable
jumper from the
TEST OUT
connector to the
TEST IN
connector on each Control Unit. Do
not connect the two units to each other on these ports.
5. Connect a coaxial cable to the master unit’s
RF OUT
connector on the rear panel. Use
another coaxial cable and repeat this step with the backup unit.
6. Connect the free end of both coaxial cables to two free inputs on the headend combiner.
Make sure that the amplitude of the Control Unit’s carrier is adjusted to the
recommended level, which is 15 dB below the adjacent video carriers.
7. Connect the female end of each power cord to the three-pin connector on each Control
Unit.
8. If you have not yet done so, plug the male end of each unit’s power cord into an AC
power source. To avoid loss of service due to a power failure, use an uninterruptible
power supply (UPS).
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