Omron C200HW, Operation Manual

Page: 49 / 285

2-4 Section Connecting External I/O
36
2-4-4 Wiring Precautions
Operational errors such as dislocation can occur in most electronic control
devices if they are subjected to electronic noise from nearby power lines or
loads. Recovery from such errors is usually very difficult and time consuming. To
avoid such noise-generated operational errors and improve system reliability,
always observe the following precautions in wiring the system.
Be sure to use the sizes and materials indicated in the specifications when con-
necting power lines and cables.
Power lines (e.g., AC power supply, motor power line) and control lines (e.g.,
pulse output lines, external I/O signal lines) must be wired separately. Never put
these lines into the same duct or make them into a single bundle.
•
Attach a 1-
µ
F multi-layer ceramic capacitor to the pulse output power supply to
improve noise resistance.
•
Use shielded cable for control lines.
•
Connect the shielded cable to the frame ground at both the Position Control
Unit and the driver.
•
Attach a surge absorber to all inductive loads, such as relays, solenoids, and
solenoid valves.
+
DC
–
Diode for surge
absorption AC Surge
absorber
RY RY
DC relays AC relays
Solenoid Surge absorber
Solenoids, etc.
Note Connect the diode and surge absorber as close as possible to the relay. Use a
diode capable of withstanding a voltage five times higher than the circuit voltage.
•
Insert a noise filter into the power supply inlet if noise enters the power line
(e.g., when it is connected to the same power supply as an electric welder or an
electric spark machine or when there is any supply generating high frequency
noise).
•
Use No. 3 or greater grounding contacts and the thickest possible wire, greater
than 1.25 mm
2
.
•
Twisted-pair cable is recommended for power lines.