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CONNECTING THE RS 485 SERIAL LINE
The following section describes the connections necessary for communication between the RB 3300 back-amplifier board and the CP 3100
control unit. Communication takes place by means of an RS 485 serial line. Using a screened cable, connect the "M3" terminal strip (ref. 21
– Fig. 1, page 72) as shown in Figure 3 on page 72. The "M3" terminal strips of the various boards must be connected together in parallel
("bus" connection), in order to make it possible to disconnect and remove one board without interrupting communication with the other
A.C.U.s. Choose the cable to be used for connections according to the following indications:
• When the line is long enough to potentially pick up disturbance along its course, use a screened bipolar cable specifically designed for di-
gital data transmission. In this case, pay attention to the capacity of the screened cable, which must be suited to the length chosen and to
the data transmission speed, which is only 1200 baud.
• When the line is relatively short (e.g. wiring between racks), make the connections using a normal bipolar cable, or preferably a twisted bi-
polar cable which has a reduced capacity but still offers good screening.
IMPORTANT NOTES
• In making connections with screened bipolar cables, connect the screen to only one end of each cable.
• When the connections are made using screened cable, only use the specific type for digital data transmission.
CONNECTING THE AUDIO SOURCE
NOTE
• In the descriptions in this section, the "following" A.C.U. (back-amplifier board) means the one which, in the group of A.C.U.s, is connected
downstream from the current one with respect to the last backup amplifier.
The source is connected by means of the "M1" terminal strip, used for the balanced input of the low level audio signal. If the "M1" terminal
strip belongs to a "NORMAL" unit, it must be connected with the audio source (generally an output of the OB 3230 AUDIO OUTPUT boards
of the system switching unit). If the "M1" terminal strip belongs to a "BACKUP" unit, it must be connected with terminal strip "M7" of the fol-
lowing A.C.U. ("NORMAL" unit number 1 or a "BACKUP" unit of a previous number).
Using a screened cable, connect the "M1" terminal strip (ref. 13 – Fig. 1, page 72) as shown in Figure 4 on page 73.
CONNECTING THE AMPLIFIER
NOTES
• In the descriptions in this section, the "preceding" A.C.U. (back-amplifier board) means the one which, in the group of A.C.U.s, is connec-
ted upstream from the current one with respect to the last backup amplifier.
• In the descriptions in this section, the "following" A.C.U. (back-amplifier board) means the one which, in the group of A.C.U.s, is connected
downstream from the current one with respect to the last backup amplifier.
The amplifier is connected using terminal strips "M4" and "M11".
The "M4" terminal strip is used for the output of the balanced audio signal, and must be connected to the input of the amplifier being con-
trolled (primary or backup amplifier).
The "M11" terminal strip is used for the input of the signal for speakers, and must be connected to the constant voltage output of the am-
plifier being controlled.
Connect the "M11" terminal strip (ref. 16 – Fig. 1, page 72) and the "M4" terminal strip (ref. 14 – Fig. 1, page 72) as shown in Figure 5 on pa-
ge 73.
IMPORTANT NOTES
• When the "fire-break" function is used (see the section "FIRE-BREAK FUNCTION"), the signal that has to drive the amplifier input must not
be picked up from the "M4" terminal strip, but from the dedicated terminal strip of the SB 3320 FAULT DETECTOR board.
• The audio signal is always available on the "M4" terminal strip, independently of activation of the "fire-break" function.
TERMINAL STRIP
CONNECTING THE SPEAKERS
NOTE
• In the descriptions in this section, the "preceding" A.C.U. (back-amplifier board) means the one which, in the series of A.C.U.s connected
to the "monitor bus" line, is connected upstream from the current one with respect to the last backup amplifier..
TERMINAL STRIP TERMINAL FUNCTION
M3 N°1: serial line GND
N°2: "hot" serial line balanced signal
N°3: "cold" serial line balanced signal
TERMINAL STRIP TERMINAL FUNCTION
M1 N° 1: audio signal GND
N° 2: "hot" balanced audio signal (low level)
N° 3: "cold" balanced audio signal (low level)
TERMINAL FUNCTION
M4 N° 1: audio signal GND
N° 2: "hot" balanced audio signal (low level)
N° 3: "cold" balanced audio signal (low level)
M11 N° 1: + high level audio signal (e.g. 25 V – 50 V – 70 V – 100 V)
N° 2: - high level audio signal (e.g. 25 V – 50 V – 70 V – 100 V)
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