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AM-8
SCADA 3000 User’s Manual
COMMUNICATIONS WIRING
The Annunciator Module communicates with the SCADA 3000 using a high-speed serial
communications bus. This 4-wire bus is used to connect up to 15 modules to the main unit to
provide additional inputs and/or outputs. Perform all wiring with power to the main unit and
modules turned off.
Modules may be located a maximum of 2000' away from the main unit and should be connected
in a daisy-chain fashion from one module to the next. Each module connects to the next via a 4-
wire communications cable connected to the terminals labeled A,B, Z & Y. The cable must be
4-Conductor Twisted Pair (shielded or unshielded) with a nominal impedance of 120Ω (for
example, Belden #8132 or 9842 cable). Use one pair for A & B and the other pair for Z & Y. The
proper wiring from the main unit to the modules, and from module to module, is shown in
Figure 3:
A
B
Z
Y
Y
Z
B
A
Y
Z
B
A
Y
Z
B
A
SCADA 3000
Module Module Module
reversed
straight-thru straight-thru
Figure 3: Correct daisy chain setup: Main unit on the end.
A
B
Z
Y
Y
Z
B
A
Y
Z
B
A
Y
Z
B
A
SCADA 3000
Module Module
Module
reversedstraight-thru
straight-thru
Y
Z
B
A
Module
reversed
Figure 4: Incorrect daisy chain setup: Main unit in the middle of the chain.
The Main Unit should always be on one end of the chain, never in the middle.
Each module must be configured with its own unique address using the BUS ADDRESS
jumpers. You may mix & match up to 15 modules to suit your application’s requirements. The
example below shows a Bus Address setting of 9.
Address Jumper Code
1 A B B B
2 B A B B
3 A A B B
4 B B A B
5 A B A B
6 B A A B
7 A A A B
8 B B B A
9 A B B A
BUS
ADDRESS
fd
1
2
3
4
A B