需求
“Create a cooling tower fan HOA ladder with auto selection and enable, hand or auto motor command, overload protection, overload alarm, and run feedback.”
接著試試Add a high-temperature auto request.Change the run lamp to a fault lamp.
這張圖裡有什麼
看懂背後的決策。
01
Use an internal bit M0 for the auto request so the Fan Command output Y0 is driven by only one coil.
02
Place the overload trip XIO after the Hand/Auto parallel branches so it unconditionally stops the fan.
03
Add separate alarm and run-feedback outputs for operator visibility.
Use when converting a hardwired HOA motor starter to PLC control where auto-mode permissives and overload protection must be enforced before the motor output.