4. Troubleshooting (PROFIBUS DP)
Countermeasure 1: Improve FG.
Grounding Screw
Slave Device
Peel the cable covering and 
secure the cable with FG clamps.
Isoelectric Line
Grounding Screw
Slave Device
Countermeasure 2: Disconnect the FG 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 grounding point, disconnect the shield wire of the signal cable and isolate it from the ground to restrain noise intrusion.
Disconnect the grounding wire.
♦Induced noise via communication cable
Separate the PROFIBUS DP 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 | ||||
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Signal wire |
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| 1 | 1 | 2 |
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PLC input/output wire
Control cable
PLC power wire 
Control circuit wire
Power cable
Power wire
| 300 mm | 2 |
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| or more |
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| Conduit |
| 1 Signal wire |
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| 300 mm |
| PLC input/output wire | |
| 1 | 2 | ||
| or more | 2 Power wire | ||
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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.
Fieldbus I/O Rev.6 | 133 |
