Powering I/O Circuits Using Separate Supplies - Automation Direct DL205 Manual

3–4
I/O Wiring and Specifications
Powering I/O
Circuits Using
Separate Supplies
AC Power
Power Input
Auxiliary
+24VDC
Supply
–
+
+
+
DC Power
– –
DL205 System
Power Input
DL205 Installation and I/O Manual, Rev. B
In most applications it will be necessary to power the input devices from one power
source, and to power output loads from another source. Loads often require
high-energy AC power, while input sensors use low-energy DC. If a machine
operator is likely to come in close contact with input wiring, then safety reasons also
require isolation from high-energy output circuits. It is most convenient if the loads
can use the same power source as the DL205 system, and the input sensors can use
the auxiliary supply, as shown to the left in the figure below.
If the loads cannot be powered from the system supply, then a separate supply must
be used as shown to the right in the figure below.
DL205 System
Input Module
Output Module
Inputs Com. Outputs Com.
Loads
Some applications will use the DL205 external power source to also power the input
circuit. This typically occurs on DC-powered systems, as shown in the drawing
below to the left. The inputs share the system power source supply, while the outputs
have their own separate supply.
A worst-case scenario, from a cost and complexity view-point, is an application
which requires separate power sources for the DL205 system, input devices, and
output loads. The example wiring diagram below on the right shows how this can
work, but also the auxiliary supply output is an unused resource. You will want to
avoid this situation if possible.
Input Module Output Module
Inputs Com. Outputs Com.
Loads
AC Power
Power Input
Auxiliary
+24VDC
Supply
–
+
AC Pow-
er
Power Input
Auxiliary
+24VDC
Supply
–
+
Load
Supply
DL205 System
Input Module
Output Module
Inputs Com. Outputs Com.
Loads
DL205 System
Input Module
Output Module
Inputs Com. Outputs Com.
Input Loads
Supply
Load
Supply
Load
Supply