Does switching an electric valve mean turning the motor’s power on and off?
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How to write a ladder diagram for a start-stop circuit? ! Thank you! !
Once the valve is fully opened or closed, the motor is stopped via feedback.
Generally, the normally open and normally closed contacts of an intermediate relay are connected to the forward and reverse functions respectively; the direction is controlled by these contacts. When the relay coil is powered, the valve opens, and when it is not powered, the valve closes. Continuous power supply is required to ensure that the valve stays in the open or closed position. (There are limits built into the valve, and once the motor reaches its extreme position in either forward or reverse direction, it will stop operating on its own.)
It is recommended to use an intermediate relay, with one set of contacts (one normally open and one normally closed) connected to the opening and closing of the valve (i.e., to control the forward and reverse rotation of the valve motor). Then, with the ladder diagram, just one output is sufficient; the output signal controls the intermediate relay. The electric valve is equipped with a limit switch; power is automatically cut off once the switch reaches its intended position, and this does not affect the continuous output of the relay. Additionally, if you want to monitor the operation of the valve, you can connect a valve position switch.
So just one output point is enough, right? !