Omron OMNUC W R88A-NCW152-DRT, Manual

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6.3 Precautions for Communications Line Design
6-17
6
„ 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.
AC input
Power
supply
circuit
Switching power supply
DC output
Casing
[Switching Power Supply Configuration]
AC power
supply
S82J power supply
S82Y-
††
N (Mounting Tool)
DC power supply
[Suspending the Communications Power Supply]
Insulating material (such as
baked board or acrylic board)
When using S82J power supply When using other power supplies