Phonetics SCADA 3000 manual Communications Wiring, Correct daisy chain setup Main unit on the end

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:

SCADA 3000 Module Module Module

A B Z Y

Y

Z

B

A

reversed

	Y		Y
	Z		Z
	B		B
	A		A
straight-thru		straight-thru

Figure 3: Correct daisy chain setup: Main unit on the end.

Module Module SCADA 3000 Module Module

Y

Z

B

A

straight-thru

Y

Z

B

A

reversed

A B Z Y

Y		Y
Z		Z
B		B
A		A
reversed	straight-thru

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.

A B

1

2

3

4

BUS

ADDRESS

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

AM-8