Regarding on-site dual-switch control
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I would like to ask the experts: how can two separate buttons be used to start the pump simultaneously, and also to stop it simultaneously? Pressing just one button is not sufficient to turn the circuit on or off. 2 buttons are placed on the control box on site.
Start pump: two normally open buttons in series； Pump stop: Two normally closed buttons in parallel.
The key issue is that starting and stopping the pump can only be done using 2 buttons – there are only 2 buttons available on site. If you press both buttons at the same time to start, and then press them again simultaneously to stop, it’s unclear how to control the pump. . .
Is there anyone experienced who can give some guidance? :dizzy:
Your situation is quite unusual – there are only two buttons, yet both of them need to be pressed at the same time to start the device, and again both need to be pressed simultaneously to stop it. Such a requirement is not common in normal cases. However, if this is indeed the required setup, it is recommended to use a control circuit with a single button; by connecting two buttons in series instead of using just one button, the requirements can be met.
I just can’t figure it out: if they’re connected in series, shouldn’t it stop as soon as one is turned off? The requirement is that both need to be turned off in order to stop the system; turning off just one one isn’t enough. I don’t know what to do. . .
A button with multiple sets of contacts should work, right?
The single-button start/stop control circuit uses normally open buttons; when two such buttons are connected in series, pressing one of them has no effect. For details on the circuit, please search on Baidu – just type \"single-button start/stop\" to find it
For starting, the two buttons are connected in series; for stopping, they are connected in parallel, so pressing one of them will not cause stopping. In a case like yours, it’s only possible to add two buttons, or a microcomputer switch, in order to achieve this.
If this is a PLC system, then it’s easy to understand. Pressing the start or stop buttons simultaneously simply provides a condition for the PLC; these are two signal buttons that can function as passive inputs