Dl205 System Isolation Boundaries - Automation Direct DL205 Manual

3–2
I/O Wiring and Specifications
I/O Wiring Strategies
DL205 System
Isolation
Boundaries
Primary Side
Power Input
+24VDC Out
DL205 Installation and I/O Manual, Rev. B
The DL205 system 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,
wiring errors, and avoid safety problems.
DL205 system 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 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 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 DL205 system, it is
extremely important to avoid making external connections that connect logic side
circuits to any other.
Primary Side
DL205 System
Main
Power Input
Power
Supply
Isolation
Boundary
The next figure shows the physical layout of a DL205 system, as viewed from the
front. In addition to the basic circuits covered above, AC-powered bases include an
auxiliary +24VDC power supply with its own isolation boundary. Since the supply
output is isolated from the other three circuits, it can power input and/or output
circuits!
DL205
System
Main
Power
Internal
Supply
CPU
Auxiliary
Comm.
+24VDC
Supply
To Programming
Device, Operator
Interface, Network
Secondary, or
Logic side
(backplane)
CPU
(backplane)
Programming Device,
Operator Interface, or Network
Secondary, or
Logic side
Backplane
Input Module
Inputs Commons
Field Side
Field Side
Input
Inputs
Module
Output
Outputs
Module
Isolation
Boundary
Output Module
Outputs Commons
Supply for
Output Circuit