Digital Monitoring Products Inc PC0128 User Manual

DMP keypads have removable covers that allow the base to be mounted on a wall or other flat surface using

the screw holes provided on each corner.
For mounting keypads on solid walls, or for applications where conduit is required, use a DMP 695 or 696

keypad conduit backbox.

Several factors determine the performance characteristics of the keypad bus: the length of wire used, the

number of devices connected, and the voltage at each device. When planning a keypad bus installation,

keep in mind the following four specifications:

1. DMP recommends using 18 or 22-gauge

unshielded wire for all keypad circuits. Do not use twisted pair 

or shielded wire for keypad bus data circuits.

2. On keypad bus circuits, to maintain auxiliary power integrity when using 22-gauge wire do not exceed

500 feet. When using 18-gauge wire do not exceed 1,000 feet. To increase the wire length or to add

devices, install an additional power supply. 

Note: Each panel allows a specific number of supervised keypads. Add additional keypads in the

unsupervised mode. Refer to the panel installation guide for the specific number of supervised keypads

allowed.

3. Maximum distance for any one bus circuit (length of wire) is 2,500 feet 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 feet. As wire distance from the panel increases, DC voltage on the wire decreases.

4. Maximum voltage drop between the panel (or auxiliary power supply) and any device is 2.0 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 710 Installation Sheet (LT-0310) and or the LX-Bus/Keypad Bus Wiring

Application Note (LT-2031).

Connect the transformer wires to terminals 1 and 2 on the panel. Use no more than 70 ft. of 16 gauge, or 

40 ft. of 18 gauge, wire between the transformer and the panel to deliver a minimum of 15.5 VAC when 

500mA of current draw is used from the auxiliary power supply terminal 7.

 

Always ground the panel before applying power to any devices: The panel must be properly grounded 

before connecting any devices or applying power to the panel. Proper grounding protects against 

Electrostatic Discharge (ESD) that can damage system components. See Earth ground, in the Secondary

Power Supply section.

The transformer for the panel is 16.5 VAC 40 VA, which provides up to 1.5 Amps of bell output current,

500mA of auxiliary current, and 100mA of smoke detector output. Use either the Model 320 wire-in or

321 plug-in transformer with the panel. The total current available is limited by the total battery standby

requirements of the installation.

 The transformer must be connected to a 120 VAC 60 Hz commercial power outlet that is not con trolled by a

wall switch. 

When either AC transformer power or DC battery power is connected to the panel the PWR LED shows steady

green.