DL06 Micro PLC User Manual, 3rd Edition, Rev. E
Chapter 2: Installation, Wiring, and Specifications
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System Wiring Strategies
The DL06 Micro PLC is very flexible and will work in many different wiring configurations.
By studying this section before actual installation, you can probably find the best wiring
strategy for your application. This will help to lower system cost and wiring errors, and avoid
safety problems.
PLC Isolation Boundaries
PLC circuitry is divided into three main regions separated by isolation boundaries, shown
in the drawing below. Electrical isolation provides safety, so that a fault in one area does not
damage another. A power line filter will provide isolation between the power source and the
power supply. A transformer in the power supply provides magnetic isolation between the
primary and secondary sides. Opto-couplers provide optical isolation in Input and Output
circuits. This isolates logic circuitry from the field side, where factory machinery connects.
Note that the discrete inputs are isolated from the discrete outputs, because each is isolated
from the logic side. Isolation boundaries protect the operator interface (and the operator) from
power input faults or field wiring faults. When wiring a PLC, it is extremely important to avoid
making external connections that connect logic side circuits to any other.
The next figure shows the internal layout of DL06 PLCs, as viewed from the front panel.
LCD monitor
4 Optional
card slots
2 comm. ports
Power
Input
16 Discrete Outputs
To programming device
or Operator interface
20 discrete Inputs
Isolation
boundary
Output circuit
Input circuit
Power
Supply
CPU
Output Circuit
Input Circuit
C P U
2 Comm.
Ports
Main
Power
Supply
To Programming De-
vice, Operator Interface
or networking
20 Discrete
Inputs
Commons
Commons
16 Discrete Outputs
PLC
DL06
Optional
Filter
Power
Input
Card Slots
LCD Monitor
