PLC ladder diagram

Doesn’t it say that when I0.3 is 1?

Pay attention to the relationship between or, 0.3 is a required item {:9001:}

This post was last edited by myface on 2021-12-29 08:50 This is a Chinese language question. This way of writing is indeed ambiguous.: It is said that the Chinese language skills of many science workers are indeed not very good, and they do not know how to explain the text more clearly and understandably. This is why the same science knowledge books have good and bad qualities.

When the signal status of input terminals I0.0 and I0.1 is "1", why will the signal status of output terminal Q4.1 be "1"? Isn't I0.3 always disconnected? According to the logic diagram you provided, suppose: When the PLC is initially powered on, when the peripheral IO signals remain in their original state, that is, the I0.0, I0.1, and I0.3 input signals are 0 (disconnected) ； I0.2 closed is high level 1. 1. After the PLC is powered on and running, at this time, Q4.0 should be I0.2 closed (1), so the Q4.0 output coil is high level 1 ； The status of Q4.1 is open circuit 0 because the I0.3 input signal is open (0). 2. If the I0.2 input signal changes and is disconnected to 0, then the status of Q4.0 and Q4.1 are both 0 status. ； 3. Suppose again that the I0.0 and I0.1 input signals are closed to 1 at the same time. At this time, the Q4.0 action closes to 1. ； 4. Then assume that I0.3 is also closed. At this time, when Q4.0 remains closed, Q4.1 is also closed and outputs high level 1. If you want to understand PLC logic diagrams, you should start from the most basic knowledge. * , step by step. For example, "I" means input signal, "Q" means output signal, etc...

I thought it was a king problem, but later I found out it was bronze (just a joke)

My first answer was not wrong, you understood it wrong