4. Troubleshooting (PROFIBUS DP)
Countermeasure 1: Improve FG.
Peel the cable covering and
secure the cable with FG clamps.
Grounding Screw
Isoelectric Line
Grounding Scre
w
Slave Device 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
Communication cable
Control cable
Power cable
Signal wire
PLC in
p
ut/out
p
ut wire
PLC power wire
Control circuit wire
Power wire
Suspended ducts Floor ducts
1
2
12
1 2
1 Signal wire
PLC input/output wire
2 Power wire
300 mm
or more
300 mm
or more
Conduit
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