Interlogix DVR 41 User Manual - Manual (Page 16)

1BChapter 2: Installation
10 TruVision DVR 41 User Manual
Wiring the keypad
The keypad uses RS-485 simplex wiring. The signal is transferred by a single
twisted pair line. A shielded STP CAT5 network cable is recommended. Ground
one end of the cable, either the first or last device on the RS-485 line.
The maximum number of devices that can be installed in one bus is 255, with a
maximum cable length of 1200 m. The cable length can be expanded using a
signal distributor.
Both the first and the last device in series should be terminated with 120 Ohm
resistance to minimize line reflections. See Figure 3 below.
Figure 3: RS-485 bus serial wiring (KTD-405 keypad shown)
1. Keypad
2. I/O box 3. See section “RS-485 ports” on page 12
Use an RS-485 signal distributor for a star wiring configuration. See Figure 4 on
page 11.