44 Rockwell Automation Publication 1766-UM001O-EN-P - September 2021
Chapter 3 Wire Your Controller
• Use Belden 8761, or equivalent, shielded wire.
• Under normal conditions, the drain wire (shield) should be connected to
the metal mounting panel (earth ground). Keep the shield connection to
earth ground as short as possible.
• To ensure optimum accuracy for voltage type inputs, limit overall cable
impedance by keeping all analog cables as short as possible. Locate the I/
O system as close to your voltage type sensors or actuators as possible.
• The controller does not provide loop power for analog inputs. Use a
power supply that matches the transmitter specifications as shown in
Figure 21 on page 44
.
Figure 21 - Analog Input Transmitter Specifications
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 is removed by the input filters.
Several specific steps can be taken to help reduce the effects of environmental
noise on analog signals:
• install the MicroLogix 1400 system in a properly rated enclosure, for
example, NEMA. Make sure that the MicroLogix 1400 system 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.
Ground 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.
IV0(+), IV1(+), IV2(+) or IV3(+)
Controller
IV0(+), IV1(+), IV2(+) or IV3(+)
Controller
+-
+
-
+
-
IV0(+), IV1(+), IV2(+) or IV3(+)
COM ANA
Controller
+
-
+
-
GND
+
-
COM ANA
COM ANA
2-Wire Transmitter
3-Wire Transmitter
4-Wire Transmitter
Transmitter
Transmitter
Transmitter
Supply
Signal
Supply
Signal
Power
Supply
Power
Supply
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