Programmable logic controller: Difference between revisions

Revision as of 18:49, 9 July 2004

Revision as of 18:54, 9 July 2004

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===Examples===

In the simple example above, the PLC is accepting two digital inputs from float switches. The PLC is controlling a single digital output to actuate the inlet valve into the tank. If both float switches are off (down) the PLC will open the valve to let more water in. It will continue to fill until both floats lift making their switches turn on.

The slightly more complex example (scale and flow controller) uses analog inputs and outputs. The scale is connected to one of the PLC's analog inputs and the flow controller is connected to one of the PLC's analog outputs. In this system, we can fill at different rates based on how much water inis left. If the water level drops rapidly, the flow controller can be opened wide. If water is only dripping out of the tank, the flow controller can be set to allow only a small amount of water back into the tank.

== Programming ==