Noise Intrusion

Verify how error occurrence condition changes while taking the following countermeasures.

• Ground of FG wire

  Normal Grounding: Peel the cable covering and ground the FG wire.

  

  Symbol	Description
  a	Peel the cable covering and secure the cable with FG clamps.
  b	Turn ON the terminating resistor at the end of the network.
  c	Secure the clamps to the intermediate plate of the board with screws to ground the shield.

Countermeasure 1: Improve FG.

Symbol	Description
a	Peel the cable covering and secure the cable with FG clamps.
b	Isoelectric Line
c	Grounding Screw
d	Slave Device

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

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

• 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.

  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.