Sensors are added to a place by selecting sensor item from the control panel and clicking on a desired place. Small filled rectangle appears next to the place, indicating that there is at least one sensor associated with the place.
After selecting a place double-clicking on the corresponding sensor icon (filled rectangle) brings up the sensor dialog as shown in the figure.
Each sensor represents a row in the table. Sensors can be added or subtracted by pressing appropriate buttons. When all rows are deleted and the dialog is closed the sensor icon for this place dissapears.
There are two types of sensors: regular and "mean" (the selection is made by means of the check box).
Regular sensor has two parameters: threshold and delay. It measures the probability that the number of tokens in the place exceeds a given threshold. The following convention is used, implying a strict inequality: in the displayed example to the right result 0.6 corresponds to the probability that at the end of the simulation there at least one token in the place (i.e., strictly more than zero tokens). Another quantity measured by a regular sensor is the number of hits, i.e., the expected number of times the threshold is exceeded for at least the time specified in the delay (1.733 times is shown in the example).
For example, specifying a sensor time delay can be used to directly evaluate power quality indices (where duration of the outage is as critical as frequency of its occurrence).
Mean sensors have two parameters (start and end time), and they provide time-averaged expected number of tokens in the place within the specified start and end time and the corresponding variance. Start and end times can be controlled uniformly for all sensors when parameter XLS spreadhseet is used parameter XLS spreadhseet is used to control parameters. The time-averaged values are written into the full report.
If the sensor parameters are changed, simulation must be re-run to update the results. Parameters not relevant for a given sensor type (e.g., threshold for the mean sensor type) are ignored by the simulation.
Sensor property shows the value at the end of simulation, and the time history for each sensor can be exported directly into a spreadsheet. The number of time steps for which the sensor information is recorded is controlled from simulation properties (under simulation time steps).
By default sensors are color blind (they count all tokens in a place regardless of their color). However, for the places that are inputs to merging by color joints the dialog an extra column placed that identifies the color of tokens being sensed. The value -1 (default) corresponds to sensing all colors. Only mean sensors can be color specific in the current version.
Color Specific Sensor Options
Sensors
