can't detect actuator status in its plc mhj edition

However, you would not want everything in your system to be indicated by pilot lights, as they occupy an output terminal at the PLC output side. Of course, there are limitless applications of these pilot lights in PLC automation or PLC control systems because they are just plain handy. The third pilot light that I put is a special case for the PLC control system-the pilot light was placed such that the temperature limit switch will turn it on.īecause of the third pilot light, the operator will know whether the PLC control system was turned OFF by another operator, or it was the high temperature that turned the motor OFF. 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. The START light will only power when the START button is pressed, as it should be. Your PLC programming would look like this: 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. This makes it REALLY easy to identify which are working, and at the same time, you also identify which should SUPPOSEDLY work or not.Īs 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. Or “Hey, something is wrong because your temperature level inside the system is too low or too high”. They are usually placed in the control system to tell the operator, for example, “Hey, you have a DC voltage output at the solenoid valve right now” Pilot Lights are almost always present in PLC automation systems. Pilot Lights Photo from Rockwell Automation

These are just the most common applications of indicators and alarms. A blinking red light, a horn, or a buzzer may represent that a hazardous condition has been met in the system. A red pilot light usually represents a PLC system that does not have ongoing operation.Īlarms provide notification with higher urgency. Indicators such as pilot lights-usually a green one, may represent that the PLC system is running properly. The indicators/alarms include devices that can represent a predetermined state in a basic PLC control system.

Can't detect actuator status in its plc mhj edition