Dry contact (limit switch)
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Everyone, for the limit switch of the on-site valve, are its normally open contacts connected such that one terminal is linked to 24V+ and the other terminal to 24V-?
In that case, the closing of the switch causes a power short circuit. So the switch is connected to the same terminal as the power supply.
It depends on what you use it for In a PLC, DCS, or electrical control circuit?
You’re really extreme. . . . It should be the positive signal and the negative signal
I already said it’s a dry contact point – it’s just the signal + and signal – terminals; where would power come from? What you need are passive points, as using them in the cabinet will cause problems
Just take a look at this wiring diagram and you’ll understand
It’s this DCS DI point circuit; wouldn’t the limit switch on site cause 24V+ and 24V- to be shorted together?
This post was last edited by hxq0374 on 2018-8-29 20:08. You’re right; indeed, 24V and ground were connected in the end. But there is a detection coil at the DI point of the intermediate DCS. It can ensure that the power supply does not experience a “short circuit”. But if you directly connect 24V+ and ground to this dry contact, it will undoubtedly cause a short circuit in the power supply, destroying the switching power supply or causing the upstream circuit breaker to trip.
What terminals do the on-site limit switches have? You can use a multimeter to measure them and find that pair of points. There’s no need for such complexity; even if you make a mistake in the wiring, the DCS’s IO circuits have short-circuit protection, so there should be no problems, as long as it’s not high-voltage electricity