Sensaphone SCADA 3000 Users manual - Manual (Page 57)

7-3
Chapter 7: I/O Expansion Modules
B and the other pair for Y & Z. Figure 3 below shows how to connect the cable between the
main unit and the modules. Note how the wiring is reversed between the modules and the
main unit, but between modules the wiring is straight through.
Figure 3: Communications Bus Wiring
The modules may be located up to 2000 feet away from the main unit. Do not run AC power
lines in the same cable or conduit as the communications wiring, as this can cause data errors.
Bus Termination
Both the SCADA 3000 main unit and the final module in the chain must be terminated. A
termination jumper is located on each device. The modules (if any) branching off the main
connection are not terminated. While the main connection between the SCADA 3000 and the
most distant module can be 2000 ft., the individual modules in-between are wired on branches
called Stub lines. Stub lines can be no more than 50 ft. from the main line. (See Figure 4)
Figure 4: Communication Cable Wiring and Bus Termination