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Specific Requirements:

System Modes

Schedule mode

The system is required to allow the user the ability to schedule automated sprinkling. The user needs to have the option of choosing to water by time or by amount of water delivered to a certain area.

The user should be able to water by:

The time mechanism must:

[Fig 1: Setting preferences for units used throughout the entire program]

[Fig 2: The dialog for scheduling by time]

The flow mechanism must:

[Fig 3: The dialog for scheduling by flow]

Other scheduling requirements:

Water pressure monitoring:

The system will monitor water pressure to the areas that are receiving flow. If water pressure for a particular zone goes below minimum levels, the user will be informed of low pressure to that zone. If pressure goes below critical levels, that zone will be turned off and the user informed with a log message. The pressure for a particular head will be as measured for its zone. The user has the option of having sprinklers that were terminated due to low or critical pressure automatically rescheduled when pressure again becomes available.

Priority assignment to zones:

The user needs the ability to prioritize zones and heads so that if low pressure requires part of the system to be shut down, zones and heads with the lowest priority can be shut off first.

Weather options:

If using the time mechanism, and wind or precipitation levels reach unacceptable levels for the system or for a zone, the user can choose to have the sprinkler system or zone shut down. The user has the option of having sprinklers that were terminated due to bad weather automatically rescheduled when the weather permits sprinkling again.

If using the flow mechanism, the user can choose to have automatic adjustments made to the amount of water delivered to certain areas. The software system will then take weather input and increase the flow if conditions demand, or decrease the flow if conditions demand. Any adjustments in flow made by the system will be written to the log database.

Weather forecasts do not affect day-to-day scheduling. Weather forecasts are strictly for informational use for the user creating the schedules. Immediate weather conditions can, however, affect the schedule as stated above.

[Fig 4: Influence of certain weather data on scheduling]

Schedule inputs (required to determine water schedule):

Schedule outputs:

Schedule conflicts:

Obviously, the natural state of the system is to not be watering. Due to this, valves/sprinklers may only be scheduled to be turned on. Valves/sprinklers cannot be scheduled to be off for a time interval. In other words, if the user would like a certain valve/sprinkler to be off during a particular time interval, then the only way to do this is to not schedule that valve/sprinkler to be on (or to not schedule any named (logical) zone that contains that valve sprinkler) during that time interval.

This does not interfere with the "rest"-state of the devices as specified in the external interfaces, since the rest state refers only to conditions where the system encounters a signal failure (power failure).

If the user tries to schedule a named (logical) zone for two different time intervals (whether by the flow or time mechanism) he/she will be informed with an error message and be required to choose one of the two schedules.

If zones overlap, when a valve/sprinkler is turned off by one schedule, the system must check to see if another schedule has that valve/sprinkler scheduled to be on. If so, that valve/sprinkler must remain on.

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