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399092.book Page 8 Friday, November 21, 2003 3:57 PM
Section 1—Hardware Setup
Connection to the Bus
Bulletin No. VVDED399092US
07/00
When connecting the ATV28 controller to the RS-485 bus:
• Make connections only to pins 3, 4, 6, and 7 of the 9-pin Sub-D cable
receptacle.
• Use a shielded cable with two pairs of twisted conductor. Cables are
available from Square D in lengths of:
— 328 ft (100 m) TSX-CSA100
— 658 ft (200 m) TSX-CSA200
— 1640 ft (500 m) TSX-CSA500
• Connect the communication reference potentials to each other.
• Do not exceed maximum line length of 3280 ft (1000 m).
• Do not exceed maximum tap-off length of 65 ft (20 m).
• Do not connect more than 18 nodes on one bus.
• Terminate both ends of the bus with a 120 Ω resistor in series with a
0.001 µf capacitor as shown in Figure 3.
E
N
G
L
I
S
H
120 Ω
D(A)
0.001 µF
D(B)
Figure 3:
8
Zt Line Terminator
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