Let’s take a look at the issue about limit switches!
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Let me tell you something more complicated: A valve has two proximity switches, A represents the open position, and B represents the closed position. According to the normal wiring, A is connected to UZO, and B is connected to UZC. However, the signal received by the DCS is just the opposite. Adjust the wires, UZO is connected to B, and UZC is connected to A. The received signal is correct, but when you remove A, the signal fed back by B is exactly the opposite. When the patch leaves the proximity switch, B shows undefined? Let's discuss this question of mine. Why is it shown as undefined? When A is removed, why does B appear opposite?
Normally open and normally closed. Electric shock. The owner must have made the wrong connection.
Check the settings of normally open, normally closed and DCS.