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Rockwell Automation Publication 2080-UM002L-EN-E - November 2021
Chapter 4 Wire Your Controller
Minimize Electrical Noise on Analog Channels
Inputs on analog channels employ digital high-frequency filters that
significantly reduce the effects of electrical noise on input signals. However,
because of the variety of applications and environments where analog
controllers are installed and operated, it is impossible to ensure that all
environmental noise will be removed by the input filters.
Several specific steps can be taken to help reduce the effects of environmental
noise on analog signals:
•
Install the Micro800 system in a properly rated enclosure, for example,
NEMA. Make sure that the shield is properly grounded.
•
Use Belden cable #8761 for wiring the analog channels, making sure that
the drain wire and foil shield are properly earth grounded.
•
Route the Belden cable separately from any AC wiring. Additional noise
immunity can be obtained by routing the cables in grounded conduit.
Grounding Your Analog Cable
Use shielded communication cable (Belden #8761). The Belden cable has two
signal wires (black and clear), one drain wire, and a foil shield. The drain wire
and foil shield must be grounded at one end of the cable.
Wiring Examples
Examples of sink/source, input/output wiring are shown below.
IMPORTANT
Do not ground the drain wire and foil shield at both ends of the cable.
Foil shield
Black wire
Drain wire
Clear wire
Insulation
D
DC COM
OUT
+V DC
S
G
+
–
24V supply
Logic side
User side
Load
Fuse
Sink output wiring example
Micro800 Sink output
