Omron OMNUC W Series Manual page 114

Communications Power Supply Noise Precautions
The communications power supply is the most important power supply in a DeviceNet net-
work. The following measures will prevent noise in the communications power supply.
• Use the recommended power supply (OMRON S82H/S82J) for communications.
• Use an independent power supply for communications.
• Make sure to install a noise filter on the primary AC input side of the communications
power supply.
• Always use a control system power supply for the primary AC side of the communica-
tions power supply that is not shared with power devices, such as inverters or motors.
If noise interference remains in cables after taking noise countermeasures, the following
countermeasures may be effective.
DeviceNet Special Cable Shielding
Suspend the DeviceNet special cable shield wire without grounding it. This will filter the
noise that flows from the ground to the DeviceNet special cable and will filter the noise cur-
rent that flows in the shield wire.
Communications Power Supply
Suspend the communications power supply without grounding it. This will also filter the
noise that flows from the communications power supply ground to the DeviceNet special
cable or the noise current that flows in the DeviceNet special cable. The switching power
supply is usually connected to the case and the capacitor as shown below. The FG terminal
must be suspended and the control board for the power supply itself must be insulated.
[Switching Power Supply Configuration]
AC power
AC input
supply
[Suspending the Communications Power Supply]
S82J power supply
S82Y -
N (Mounting Tool)
When using S82J power supply
6.3 Precautions for Communications Line Design
Switching power supply
Power
supply
circuit
DC power supply
When using other power supplies
6-17
DC output
Casing
Insulating material (such as
baked board or acrylic board)
6