MESSAGE Jumper Marking Jumper Marking
PRIORITY J9
NO NC
J12
R M
TONE1
PRIORITY J10
NO NC
J14
R M
TONE 2
PRIORITY J11
NO NC
J13
R M
TONE 3
PRIORITY J5
NO NC
J8
R M
TONE 4
PRIORITY J4
NO NC
J7
R M
TONE 5
PRIORITY J3
NO NC
J6
R M
TONE 6
Notes: 1. NO NC configures an individual chan-
nel to interface to normally open (NO) or normally
closed (NC) contacts.
2. R M configures an individual channel
to interface to a latched contact (R) or a momentary
contact (M).
Table 3-1.
B. A message can be activated from the
tone activation inputs on TB1. A dry contact, either
normally open or normally closed depending on the
configuration, connected between the associated mes-
sage (TB1-1 through TB1-6) and COM (TB1-7) will
activate a tone. The configuration of these channels
is described in paragraph 3-3. These inputs are opto
coupled to reduce the possibility of noise on the signal
lines falsely activating a message.
C. There are two sets of contacts which can be
used to monitor the status of a CommCenter. When
power is applied, a relay with form C contacts is
activated. These contacts are connected to TB2 and
are labeled Power Monitor Relay. The second set of
contacts monitor activation of any of the six messages
or a cascaded input. These contacts are labeled Push
To Talk (PTT) on TB1.
Do not perform any installation or mainte-
nance to the system when power is on.
3-5. POWER.
In order to prevent power to a CommCenter
from being turned off accidentally, the unit does not
have a power switch. A 300MB can be operated on
either 120VAC, 50/60 HZ or 24VDC input power.
Failure to follow all safety precautions and
instructions may result in property damage
serious injury, or death to you or others.
Do not perform any installation or mainte-
nance on this system when power is on.
This device is to be installed by a trained elec-
trician who is thoroughly familiar with the
National Electrical Code and will follow the
NEC guidelines as well as local codes.
The selection of the mounting location for this
device, its controls, power supplied, and the
routing of the wiring is to be accomplished
under the direction of the facilities engineer
and the safety engineer.
If operation on 120VAC is desired, 120VAC is
input through the 3-position field wiring terminal
block located at the back of the unit. Two knock-out
openings are provided. One knock-out should be
removed and provided with a bushing through which
the power lines can be routed into the field wiring
compartment. The 300MB is factory set for 120VAC
operation. If operation on 240VAC is desired, switch
SW1 must be set to the 240V position.
If operation on 24VDC is desired, 24VDC is in-
put on the two terminals shown in figure 3-1. Remove
the labeled jumper from terminals TB2-7 and TB2-8
of terminal block TB2, before using these positions. If
24VDC operation is chosen, a Class II power supply
and its associated wiring should be installed. Refer to
paragraph 3-4.D. if the power down option is desired.
3-6. AUDIO INPUT.
There is a provision for a low level, low imped-
ance audio signal input at the rear of the unit. It has
been designed to accept a cascaded input from a slave
CommCenter, TB2-1, but it could be audio from a
telephone system, radio receiver, CD player, or tape
player. When the enable pin on the cascade input is
pulled to circuit ground, TB2-2, audio on the cascade
in signal line is gated through the CommCenter and
output on the signal lines. As stated before, this input
is the lowest priority. The audio level input should be
1Vp-p. When cascading units, connect the slave unit’s
enable signal out terminals to the master unit’s
3-2
