This program is made up of 4 levels of programming.
The physical IO level. For a VFD, there are special Powerflex525 logic programming blocks. Not all physical IO has a programming block.
The device level. This would be a limit switch, constant speed motor, variable speed motor, level switch, solenoid valve, etc. Devices control physical IO at the physical IO level.
The equipment level. As mentioned above, this runs large modular parts of the system that work together. For instance, raw ingredients addition would be a subsystem of a chemical mixing system. Equipment Modules control devices at the device level.
The unit level. This is the logic that drives and controls all the equipment levels. It is considered the whole system level.
The sequence of operations should be written out before programmed to get a basic understand of the theory of operations of the equipment as described above. Below is a simple sequencer and some of the things that should be considered when writing the theory of operation.
