GE IC300TIU201, IC300TIU101, HE500TIU100 manual GFK-1819 Can Wiring Rules, Can Network Cabling

PAGE 40	06 Apr 2000	CH. 8: NETWORKS
GFK-1819

8.5CAN Wiring Rules

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IE L D

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V- C N

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1 2 1 Ω

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1 2 -2 5 V D C

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L	IE L D	H
V- C N	S H	C N	V +

1 2 1 Ω

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B L K	B L U 1 2 1 Ω	W H T	R E D H IE L D
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B L K	B L K			Ω
		LK	LU	1	HT	ED
B L U	B L U			1 2
W H T	W H T	B	B		W	R
R E D	R E D

S H IE LD S H IE LD

Figure 8.3 – CAN Network Cabling

1.Wire the CAN network in a daisy-chained fashion such that there are exactly two physical end-points on the network.

2.The two nodes at the physical end-points need to have 121 ohm 1% terminating resistors connected across the CN_L and CN_H terminals.

3.Use data conductors (CN_L and CN_H) that are 24 AWG shielded twisted pair for “thin cable” and 22 AWG shielded twisted pair for “thick cable”. They must also have 120-ohm characteristic impedance. In typical industrial environments, use a Belden wire #3084A (“thin”). Use #3082A (“thick”) for environments where noise is a concern.

4.Use power conductors (V- and V+) that are 18 AWG twisted-pair for “thin cable” and 15 AWG twisted- pair for “thick cable”.

5.Connect the V- power conductor to a good earth ground at one place only on the network, preferably physical endpoints.

6.For a section of cable between two nodes, the cable shield is connected to the cable shield input at one end of the cable only.

7.A CAN network (without repeaters) is limited to 64 nodes (with 63 cable segments) with a maximum cable length of 1500 ft.

8.Up to four CAN network segments, which adhere to the above rules, may be connected together using three CAN repeaters. In this manner, a CAN network may be extended to 253 nodes with a total cable distance of 6000 ft.