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3.9
Relay Operations
The following describes operation of each of the relays.
• CML relay (Connect Modem to Line relay)
This relay is for switching between the facsimile and the telephone (hand-
set or extension telephone) that is the core function of the NCU board.
With regular relays, an instantaneous circuit interruption occurs at switch-
ing. If a regular relay is used for the CML relay, there is the possibility that
the
an early make break relay designed to prevent short breaks is used for the
CML relay.
• H relay (Hook relay)
This relay is for enabling detection of the off-hook state on the telephone
(handset or extension telephone) during facsimile communications. As the
CML relay switches to the facsimile side during facsimile communica-
tions, the voltage is not supplied to the off-hook detection circuit. When
the H relay switches to the voltage terminal for off-hook detection, voltage
is supplied to the off-hook detection circuit to enable detection of the off-
hook state of the telephone even during facsimile communications.
• P relay (Pulse relay)
This relay is for generating the dial pulse (DP). A relay is used for prevent-
ing chattering or sparks.
• S relay
This relay is for shaping the pulse waveform that is generated by the P
relay. A relay is used for preventing chattering or sparks.
• R relay
This relay is exclusively for 230 V regions. It is used for sending signals to
a private branch
is used for this relay.
exchange
will malfunction because of this short break. For this reason,
exchange
when the R key is pressed. A photo-MOS relay
FACSIMILE SYSTEM
1
2
3
4
5
6
ït
çi
6–17
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