Controls Library

Alarm

Model

This model provides a warning message and changes color if a process variable exceeds the LL, L, H, or HH alarm points. Connect the Alarm like you would connect a PID model, or create a flowsheet equation linking the PV variable to another variable in your simulation.

ASC

Model

This model represents a prototype compressor anti-surge controller (ASC) to protect compressors from surging. This model takes an input from a Process Library Compressor model and provides an output to a Valve model. The Compressor model will indicate its proximity to surge.

Hold

Model

This model allows you to hold a transmitter or controller signal constant for a time interval that you set.

Integral

Model

This model allows you to integrate a process variable over time. You can connect it to another controller, to a transmitter, or by using a flowsheet equation.

Measure

Model

This model allows you to perform data reconciliation on your simulation by using measurements from your distributed control system (DCS) or data historian. Data reconciliation is an important step when tuning a simulation to match measured process data. After adding Measure models to your simulation and linking (or manually specifying) the Scan values, you can perform an optimization to minimize the global measurement error (TotalError) of your simulation.

OnOff

Model

This model represents a controller that turns on or turns off when a desired high or low value is achieved. This model maintains the process value between high and low limits.

PID

Model

This model represents a Proportional-Integral-Derivative (PID) controller with integral windup protection used for pressure control.

RateLimit

Model

This model limits the rate of change of the input based on the RLu and RLd values.

Select

Model

This model enables the implementation of control logic in which multiple PID output signals are connected to a single final control element (for example, a control valve). This model supports two input signals. Depending on the Type, it passes either the higher or the lower of the two input signals to the final control element while ignoring the other.

Split

Model

This model provides a split range function that you can apply to a PID output signal. This model can have any number of outputs.

Switch

Model

This model enables the implementation of control logic in which a single PID output signal is connected to multiple final control elements (for example, control valves). During operation, this model passes the PID signal to a single control valve while the other valves effectively remain in manual operation.

TimedGenerator

Model

This model generates timed values that allow you to vary a model variable with time, such as a Source pressure. Typically, you use the TimedGenerator with a flowsheet equation that modifies the model variable based on the generated value.

The TimedGenerator model uses a Curve to generate values. By default, the TimedGenerator uses the TimedExample Curve from the Controls Library, which provides a generic sine wave with an amplitude of one and a wavelength of 360 seconds. You can copy this Curve into your simulation-specific Model Library and then modify the Curve to create your own trend of time-generated values. You can then update the ExampleTrend parameter in your TimedGenerator model to use your new Curve to generate values.

Trans

Model

This model represents a transmitter that can connect to a PID or other control model.

Trim

Model

This model allows a PID controller to trim a feed forward control. This model adds the feed forward input from a process variable (typically from a Transmitter) to the control input of a PID controller that is used to trim the feed forward process input. It can either provide a remote setpoint to a secondary controller or provide its output directly to a control device such as a valve.

Wave

Model

This model represents an oscillatory signal generator. The output signal follows wave functions of the sinusoidal, triangular, sawtooth, and square type. You can specify the upper and lower values of the curve.