4. Troubleshooting (DeviceNet)

Countermeasure 2: Disconnect the shield wire to isolate it from the ground.

When noise intrudes the ground line because a noise source such as an inverter is installed near the communications power supply, disconnect the shield wire of the communication cable and isolate it from the ground to restrain noise intrusion.

Power Supply Tap

V+

V+

 

CAN H

CAN H

 

Shield (S)

Shield (S)

DeviceNet cable

CAN L

CAN L

 

V-

V-

 

V+ V- S

Disconnect here.

V+ V- FG

Ground 100 Ω or less.

Communications

Power Supply

24 V DC

Induced noise via communication cable

Separate the DeviceNet signal wire from the other wires (especially power wires).

* Separate the signal wire from the power wires 300 mm or more.

 

Light electrical cable

Suspended ducts

Floor ducts

 

Communication cable

 

 

 

 

 

Signal wire

 

 

 

 

 

1

 

1

2

PLC input/output wire

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

300 mm

2

 

 

 

 

 

 

 

 

 

 

 

Control cable

 

or more

 

 

 

 

PLC power wire

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Control circuit wire

 

 

 

Conduit

 

1 Signal wire

 

 

 

 

 

 

 

 

300 mm

 

PLC input/output wire

 

 

 

 

 

 

 

 

 

1

2

 

Power cable

 

or more

2 Power wire

Power wire

During site inspection, bypass the wire that is possibly affected by induced noise with other cables and then lay the cables. Establish the communication under no induced noise condition and verify whether an error occurs.

102

Fieldbus I/O Rev.6

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Epson EM07ZS1647F manual Induced noise via communication cable