GPS-X Technical Reference

Tools Object 342
One menu of parameters is defined for the lowpass model. It is accessed from the Tools Process
Data menu by selecting Parameters > Filter Settings. The available parameters are detailed
below:
Input signal: The cryptic name of the variable to be filtered.
Filter type (Analog / Digital / Analog+Digital / Off): The value of this parameter
determines whether the signal flows through the analog or the digital filter, or both.
Analog filter cutoff frequency: The corner frequency of the first-order analog filter, or
the reciprocal of its time constant.
Digital filter time step: The value of the time interval used in the digital filter model. It
is also used as the sampling time when Sample and hold is set to ON.
Digital filter cutoff frequency: The corner frequency of the first-order digital filter, or
the reciprocal of its time constant.
Sample and hold (ON - OFF): The value of this parameter determines if the digital
filter output is sampled and held for the sampling period specified above.
Digital filtering without sampling is useful if the filtered signal is to be used in a unit that already
implements a sample-and-hold on its input.
ON/OFF CONTROL
On/off controllers are simple forms of feedback control. This type of controller is used in a wide
variety of common applications. For example, household heating and cooling systems operate
using on/off control.
Using ON/OFF Controllers
An on/off controller model (onoff) is available in the Tools object. Once this model has
been selected, several parameters can be adjusted. These parameters are divided into two
groups: control variable parameters, and manipulated variable parameters. The control
variable parameters are accessed by selecting Parameters > Control Variable from the
Tools Process Data menu. The manipulated variable parameters are accessed by
selecting Parameters > Manipulated Variable from the Tools Process Data menu.
GPS-X Technical Reference