Detcon 880A-N1R, Operator'S Installation And Instruction Manual

Page: 39 / 45

880-N1R
880-N1R Instruction Manual Rev. 0.0 Page 35 of 38
Device Hook-Up
Installation should begin by deciding where devices will be located and how the connections between devices
and the master will be established. The ideal scenario would look like Figure 43. The example shows the 880
Controller connected to 11 slave devices using a daisy-chain wiring scheme. This would require 2 different
twisted pair cables, one pair for power, and the other for the RS-485 data bus.
Connections would be point-to-point starting at the master and running to the last slave. The RS-485 data
cable should come into the sensor enclosure and be connected to the A & B terminals. The next segment of
cable should also connect to the A & B terminals and leave the enclosure headed for the next device. The
shields must be tied together inside the enclosure and not allowed to short to any other wires or surfaces. The
shield should be connected only inside the Model 880 cabinets to the shield terminal. The Rt label in the
drawing shows where the termination resistors would be installed.
Figure 43
Daisy Chain wiring diagram
09
08
0a
Control Room
01 02
07 06
0b
04
05
03
Rt
Rt
Daisy Chain Wiring is ideal, although wiring may already exist or the wiring cannot be run this way for some
reason. Figure 44 shows a more realistic wiring situation that may occur.
Figure 44
Unbalanced Data Bus
01 02
03
05
06 07
09
08
04
0a 0b
Control Room