I have a question regarding three-wire proximity switches
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There is a three-wire proximity switch in the plant that needs to be connected to the DI card of the DCS. The problem is that the DI terminal already provides 24V power, and when the three-wire proximity switch is activated, it also generates 24V voltage, which prevents the DCS from receiving the signals correctly. May I ask what the best way to handle this is? I’ve now attached a 24V switching power supply to this proximity switch; the signal line is connected to a relay, and the normally open contact of that relay is connected to the DI terminal. But it seems like this approach isn’t very logical at all Could you all give me some guidance? Thank you. (It’s actually a four-wire proximity switch; I’m not sure what the white wire is for.) ）
I guess it’s a proximity switch with a three-level regulated output, meaning that the signal terminal outputs high and low voltage levels, such as 0/12V. . . A level signal is applied to the signal terminal of the relay, thereby controlling the on/off state of the relay.
I don’t think it exists. In a three-wire system, there is the positive power supply terminal, the common terminal, and the contact terminal; simply connect the common terminal and the contact terminal to the system – connecting the common terminal to 24V is sufficient
The DI points of the DCS card are available in two forms: passive dry contacts and active 24V signals; you can simply adjust the configuration or wiring to use the appropriate type
Dry contacts and wet contacts can be swapped with each other; a relay can also be used to convert wet contacts into dry contacts.