Use Persistence to stop momentary changes in point value from changing the state of a point. This stops the outstation from processing fleeting changes in point state and reporting those fleeting changes to the server. When a point that supports persistence changes value, any change of point state is delayed until the point remains in the new state for a specified amount of time. If the point does not remain in the new state for the required amount of time, no change in point state is recorded.
Use the Persistence feature to stop Geo SCADA Expert from raising change of state alarms and logging change of state events when a point value is fluctuating.
On Kingfisher outstations, many point types support persistence (only counter points do not support persistence).
Configure the required persistence settings using the Persistence field for analog points, and the Persistence section for digital points. In both cases, these fields are on the <Point Type> tab of the Point Form. For further information, see the examples below and the appropriate point configuration section.
Example 1 - Using Persistence with an Analog Point
An analog point has this configuration:
High-High Alarm Limit = 80
High Alarm Limit = 70
Low Alarm Limit = 20
Low-Low Alarm Limit = 10
with this Persistence setting:
At 12:00:00 the point value is 50 (Normal).
At 12:00:23 the point value increases to 73, which is above the High Limit.
At 12:00:28 the point value is still 73, so the point state changes to High, as it has been 5 seconds since the value crossed the High Limit from the Normal state.
At 12:00:38 the point value rises further to 84 (the High-High Limit).
At 12:00:40 the point value drops to 78, so the point state of High remains unchanged, as the point was in the High-High range for less than the Persistence time.
Example 2 - Using Persistence with a Digital Point
A 1-bit digital point is configured to show the state of a pump (running, or stopped). The point states are configured as:
State 0 = Pump Running
State 1 = Pump Stopped
The Persistence settings are:
The pump is not running so the point is in State 1. The pump starts to run then stops again after 2 milliseconds. The point state remains unchanged as the pump did not run for the duration of the Leaving Other States persistence time (three milliseconds).
The pump starts to run and remains running. After three milliseconds, the pump is still running so the point state changes to 0. The change is reported to the server the next time that the driver scans the outstation. The reported data is processed and Geo SCADA Expert raises or logs any alarms or events that are configured for State 0.
The pump stops running and remains stopped. After five milliseconds (the Leaving State 0 persistence time), the pump is still not running. The point state changes to 1. The change of state is reported to the server the next time that the driver scans the outstation. The reported data is processed and Geo SCADA Expert raises or logs any alarms or events that are configured for State 1.