You can connect devices to the LX-Bus/AX-Bus and Keypad Bus through the PROG, LX500, LX600, LX700, LX800, and LX900 4-pin headers and the keypad bus. Several factors determine the DMP LX-Bus/AX-Bus and keypad bus performance characteristics including the wire length and gauge use, the number of devices connected, and the voltage at each device. When planning an LX-Bus/AX-Bus and keypad bus installation, keep in mind the following information:
- DMP recommends using 18 or 22-gauge unshielded wire for all LX-Bus/AX-Bus and keypad circuits. Do not use twisted pair or shielded wire for LX-Bus/AX-Bus and keypad bus data circuits.
- 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 that is listed for Fire Protective Signaling, power limited, and regulated (12VDC nominal) with battery backup. Each panel allows a specific number of supervised keypads. Add additional keypads in the unsupervised mode. Refer to the Keypad Bus section for the specific number of supervised keypads allowed.
- 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. Maximum number of LX-Bus/ AX-Bus devices on the first 2,500 foot circuit is 40 devices.
- Maximum voltage drop between the panel (or auxiliary power supply) and any device is 2.0VDC. 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.