Digital Monitoring Products, Inc. | 7800 Series Installation and Programming Guide
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DMP recommends using 18 or 22-gauge unshielded wire for all keypad
and AX-Bus/LX-Bus circuits. Do not use twisted pair or shielded wire for
AX-Bus/LX-Bus and Keypad Bus data circuits. All 22-gauge wire must be
connected to a power-limited circuit and jacket wrapped.
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On Keypad Bus circuits, to maintain auxiliary power integrity when using 22-gauge
wire do not exceed 500 ft. When using 18-gauge wire do not exceed 1,000 ft. To
increase the wire length or to add devices, install an additional power supply that
is listed for Fire Protective Signaling, power limited, and regulated (12/24 VDC
nominal) with battery backup.
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Maximum distance for any one bus circuit (length of wire) is 2,500 ft regardless of
the wire gauge. This distance can be in the form of one long wire run or multiple
branches with all wiring totaling no more than 2,500 ft. As wire distance from
the panel increases, DC voltage on the wire decreases. Maximum number of
AX-Bus/LX-Bus devices per 2,500 ft circuit is 40.
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Maximum voltage drop between the panel (or auxiliary power supply) and any
device is 2 VDC. If the voltage at any device is less than the required level, add
an auxiliary power supply at the end of the circuit. When voltage is too low, the
devices cannot operate properly.
For additional information refer to the panel’s Installation Guide or the 710 Installation
Sheet (LT-0310).
KEYPAD BUS WIRING SPECIFICATIONS
Note:
Each panel allows a specific number of supervised keypads. Add
additional keypads in the unsupervised mode.
