5. Object descriptionsΒΆ

The UNICOS-CPC package contains a set of objects classified by their functionality. There are four main object categories: I/O, Interface, Field and Control objects:

  • I/O Objects : Input/Output information. These may refer to the PLC periphery, fieldbuses or just the internal memory.
  • Interface Objects : Parametrization and status (may also include periphery information). These objects are lighter than the I/O objects.
  • Field Objects : model the physical field equipments (e.g.: valves, motors, ...). The field objects are always connected to I/O objects.
    • Local : represents equipments only driven in local mode (e.g.: manual valves).
    • OnOff : represents equipments driven by a digital signal (e.g.: Digital valves, motors).
    • Analog :represents equipments driven by an Analog signal (e.g.: Control valves).
    • Anadig : represents equipments with an Analog input and a digital output (e.g.: Heater driven by PWM: Pulse Width Modulation).
    • AnaDO : represents equipments driven by a digital signal and by an analog signal for the positioning (e.g. Electrical Heater activated by a Boolean signal and positioned by an analog reference, Variable Frequency Drive, ...)
    • MFC : represents specific equipments driven by an Analog signal (e.g.: flow Set Point) with a digital output signal and a flow measurement. (Mass flow controller)
    • Stepping Motor : represents moving devices (linear or rotating) driven by an Analog signal (e.g.: Rotating mirror for optics).
  • Control Objects : performing process logic control actions, alarms and interlocks, and feedback control. They are always acting on Field Objects
    • PCO : Process Control Objects give orders to their affected fields or to dependent PCO objects.
    • Controller : Objects which contains a feedback regulation mechanism. The default method is the PID (Proportional, Integral and Derivative) algorithm.
    • Digital Alarm : Objects which triggers an alarm signal from a Boolean value
    • Analog Alarm : Objects which triggers an alarm signal with respect to an analog value (includes alarm (HH/LL) and warning (H/L) thresholds)