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Interface
Lecture 9B
Dr. Sheng-Jen Hsieh
What is a relay?
An electrical-mechanical device used to control
two different circuitry with different power
requirements
It contains a coil and contact(s); as you provide
the power to the coil, it generates magnet force
which makes N.O. (normally open) contacts
become Closed and N.C. (normally closed)
contacts become Open.
What are the applications
of a relay?
Turn on a motor requires a high voltage
To reverse the motor rotation
How to do the wiring?
Wiring Interface Between Relay and PLC Modules