DM1200 Digital Communicator/Modem 12-4
DM1200 INSTALLATION
BABT Approval Compliance
● The DM1200 has been approved for use of the
following facilities:
Loop Connect, Auto-calling, Auto-dialling, MF
dialling, Automatic repeat attempts, Series
connection, Operation in the absence of proceed
indication, and Auto-clear from call-originating end.
Any other usage will invalidate the approval of the
apparatus if as a result it then ceases to conform to
the standards against which the approval was
granted. The DM1200 is suitable for connection to
any BT PSTN circuit with loop-disconnect or multi-
frequency dialling.
● Series Connection: The DM1200 has a Series
Equivalent Number (SEN) of 0.3. The SEN represents
the portion of the maximum allowable impairment
which is taken up by a series apparatus. The
DM1200 has a nominal insertion loss of 0.025dB,
and a nominal series resistance value of 195
milliohms.
Note To avoid occasional difficulties in making calls
from other apparatus connected to the telephone
network via more than one series apparatus, or
problems in telephone conversation between both
parties, the total of SEN values of all series apparatus
should not approach or exceed 1.0. If such difficulties
are experienced, the user should consult the accredited
service engineer and NOT the telephone company. An
associated telephone may only be connected via the
series connection provided – that is, it should be
connected to the C and D terminals on theDM1200, NOT
in parallel with the A and B connections.
● Connection of the DM1200 to a main apparatus that
requires shunt wire connection is not permitted. The
DM1200 may cause bell tinkle. This product is BABT
approved and should carry the BABT approval label.
Power Supply
The DM1200 operates using 12Vdc with a current
consumption in a quiescent state of 50mA and a
maximum current requirement of 100mA when active.
Use the connection directly from the PSU inside the
cabinet. Do not use the +12V from the 3GS PCB.
The 12 volt supply is monitored and a low battery signal
is generated if the supply drops to 10.5V +/- 0.5V for
longer that 15 seconds.
Should the 12Vdc required for operation be taken from
another power source, the following warning must be
adhered to.
WARNING:
The DM1200 is intended for use with a
low voltage supply of 12Volts D.C. (typically 1A psu),
which is normally derived from the 3GS PSU as shown in
the diagram opposite. The DM1200 has no user
protection against excessive supply voltages, and users
should ensure that any power supply or other equipment
used in conjunction with the DM1200 complies with the
relevant legal safety requirements when properly
assembled, installed and maintained, and used correctly.
The DM1200 should be located and secured in its
designated position within the host panel and suitably
isolated (by stand-off bushes) from the host panel main
PCB and from any mains supply or excessive voltage
source, by a minimum clearance distance of 10mm.
PTT Line Connection to PSTN
The DM1200 is connected to the PSTN at terminals A
and B (see diagram overleaf). A connection to Earth must
also be made. If it is required to connect another device
to the line (for example, a telephone), it should be
connected at C and D.
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