Page 243 - Electronic Mechanic - TP - Volume - 2

ELECTRONICS MECHANIC - CITS

This makes it REALLY easy to identify which are working, and at the same time, you also identify which should
SUPPOSEDLY work or not.
As an example, let’s say you want to power a motor when a START button is pressed, and make it stop immediately
when the STOP button is pressed.

You know that the motor shaft creates a lot of friction at the output side, and so you set a temperature threshold
using a temperature limit switch placed at the object in contact with the output shaft.
Your PLC programming would look like this:

Notice that I put 3 indicator lights. The START light will only power when the START button is pressed, as it should
be. The STOP light will only be turned on when the motor is not running, so by default, this should immediately be
turned ON if we just supply power to the PLC.

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CITS : E & H - Electronics Mechanic - Exercise 180