• Discrete Device Object

• The DiscreteDevice object is a general purpose ApplicationObject that represents a large class of physical equipment common in manufacturing, such as pumps, valves, motors, and conveyors.
• These devices have two or more discrete physical states (for example, Open, Closed, and Moving).
• The state names are configurable and are mapped to both input and output Boolean combinations in truth-table form. The meaning of the states depends on the type of discrete device. For a pump, the states might be configured as "Off" and "On," while for a valve they might be configured as "Open," "Closed," and "Moving." 
• Note that a control valve has a continuous position represented by an analog signal of 0 to 100% and is not properly represented with a discrete device.
• Control valves are best represented with the AnalogDevice object.

• DiscreteDevice Object States

• The DiscreteDevice object has two key attributes that represent the current state (PV) and the commanded state (Cmd). Both of these are enumerations. The DiscreteDevice object can have up to five states that can be configured with state names that are appropriate to the equipment being monitored. The actual meanings of the states are dependent on the equipment:
• Passive: The passive state represents the state of the discrete device when it is idle, stopped, or closed (the typical non-running position). For example, the passive state for a motor might be "Off."
• First Active: The first active state (Active1) represents the state of the discrete device when it is considered to be running. For example, the active state for a motor might be "Forward." You can use outputs to control the first active state.
• Second Active: (Optional) Some discrete devices have more than one active state. For example, a motor might have a second active state of "Backward." You can use outputs to control the second active state (Active2).
• Transition: (Optional) The discrete device is in a transition state any time it is changing from one valid state to another. For example, if you have a valve with a passive state of "Off" and an active state of "On," the transition state might be "Moving."
• Fault: The fault state occurs when the feedback that is coming from the field is incorrect or impossible based on how the discrete device works. For example, a fault would occur if the Hi and Lo limit is being reached at the same time for a single device. Examples of fault state names are "Error," "Bad," or "Broken."