For a two-coil solenoid valve, how is it represented in a cause-and-effect logic diagram to indicate that one of the coils is disconnected?
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Once the cover is opened, the travel switch detects that the cover has reached its fully open position and shuts off the solenoid valve. However, it does not prevent shutdown. If, in the causal logic diagram, the travel switch being in the correct position causes the solenoid valve to close, does that mean the cover cannot be returned? How can one represent cutting off one of the coils of a solenoid valve in a causal logic diagram?
If it’s a solenoid valve with two coils, then in the commands to open or close the valve, two signals are outputted instead of just one – one for opening and one for closing. As for the signal indicating the valve’s position, it’s also not a single signal but two: for example, when the limit switch signals that the valve has reached the open position, the command to open is stopped; and when the signal indicates that the valve has reached the closed position, the command to close is stopped. There’s nothing wrong with this. This functional block is somewhat similar to the control module used for electric on/off valves. It is even possible to hold it in a neutral position, that is, neither opening nor closing the valve, allowing it to remain in some intermediate position. The name of the functional block depends on what control system you are using What brand? It might be different
I understand this logic, but I don’t know how to create a causal matrix diagram; if a valve occupies one tag number, it’s not possible to represent the valve’s status.
You need to understand that the so-called address isn’t one address per valve. For example, for a control valve, there is an address assigned to the valve position setpoint and another address for the valve position feedback. For a single-electromagnet cut-off valve, there is an address for the on/off command, as well as separate addresses for when the valve is fully open and when it is fully closed. How can you think of it as one address per valve?
In this case, the coils that need to be detailed are those in the causal logic diagram.
Not only in the logic diagram, but also in the PID diagram, each signal related to the control valve has its own tag number