The basic principle of using events to trigger actions in your program is that you can test each of the events to determine if it is tripped. An event is tripped if:

• The event is armed. An event gets armed by an RTCWriteEvent or by being tested outside the “golden minute” (the actual minute the event is set for), AND
• The current minute (now) is the same as the minute for which the event is set, AND
• The current day is a day for which the event’s Day mask is set, AND
• The event has not already been read as tripped today (except altering event settings re-arms it).

There are 2 instructions for configuring events:

RTCReadEvent n

Reads event register n to the HH, MM and DM registers for display and/or modification

RTCWriteEvent n

Writes HH, MM and DM to event n after modifications

There are 3 instructions for testing events. These are:

GoIfRTCEvent n,Line

If event n has tripped, goes to the named program Line.

WaitForRTCEvent n

Waits for event n to occur. This can only be used in a MultiTrack task.

RTCTestEvent n

If event n has tripped, pushes True into X. If the event has not tripped pushes False into X.

Note that the event number in all cases is subject to IasJ: precode and, if used inside a MultiTrack task, jndexing.

Please refer to the product documentation for your particular controller to find out how many events it supports.

Example:

In an energy management system for a 24-7 food store, the outside lights are to be turned on according to the following monthly schedule:

The program has 3 MultiTrack tasks. The actual turning on and turning off of lights is done by LightsOn and LightsOff. These are simple “3-liners” that simply wait for their respective events then perform their action.

The turnon and turnoff events are maintained by a task called UpdateTimes. UpdateTimes is more interesting. It pre-loads events 0 and 1 according to a schedule stored as a table in NVEM page 0. UpdateTimes is itself run once a day using event 7, which it presets itself to trip at midnight, when first launched.

It is not actually necessary for the times to be refreshed every midnight. If they are set at start-up it will be enough. However by doing it this way we open the door to a system that can have the times changed either through a built in user interface, or by a remote communications facility. Testing events repeatedly in a looping MultiTrack task, like this example does, is a good way of meeting the requirement that an event needs to be tested outside the “golden minute” in order to be re-armed.

OutSideLights   oEQU    0

                LaunchTask              UpdateTimes
                LaunchTask              LightsOn
                LaunchTask              LightsOff
                RunTasksForever

;Task to turn on the lights at the right time each day
LightsOn:
                WaitForRTCEvent         0
                On                      OutSideLights
                GoTo                    LightsOn

;Task to turn off the lights at the right time each day
LightsOff:
                WaitForRTCEvent         1
                Off                     OutSideLights
                GoTo                    LightsOff

;Task that keeps the turnon and turnoff event times updated
UpdateTimes:
                GoSub                   SetEvents       ;Initialize the events
                LoadX                   23              ;Preset event 7 to midnight every day
                RTCPopHH
                LoadX                   59
                RTCPopMM
                LoadX                   255
                RTCPopDM
                RTCWriteEvent           7
UpDateTLoop:
                WaitForRTCEvent         7               ;Wait for midnight
                GoSub                   SetEvents       ;Refresh the events
                GoTo                    UpDateTLoop

SetEvents:
        ;Refresh the turnon and turnoff events
                NVSetPage               0               ;Select NVEM0 page
                NVSetPtr                OLTable         ;Point to table of on/off times
                NVSetRecLen             4               ;4 bytes per table entry
                RTCReadDate                             ;Get the date
                RTCPushMM                               ;Access the month
                DecX                                    ;Months are 1-12, table is 0-11
                NVPopRecNum                             ;Point to table entry

                RTCReadEvent            0               ;Turn on time
                NVPushByte              0               ;Turn on hour
                RTCPopHH                                ;Store Turn on hour
                NVPushByte              1               ;Turn on minute
                RTCPopHH                                ;Store Turn on minute
                RTCWriteEvent           0               ;Save updated event

                RTCReadEvent            1               ;Turn off time
                NVPushByte              2               ;Turn off hour
                RTCPopHH                                ;Store Turn off hour
                NVPushByte              3               ;Turn off minute
                RTCPopHH                                ;Store Turn off minute
                RTCWriteEvent           1               ;Save updated event

                Return

;The following must be placed at the end of the program, after all executable code:

                NVEM0

;Table of turn-on and turnoff times. Each entry is 4 bytes,
;being HH(on), MM(on), HH(off) and MM(off)
OLTable:
                NV0Byte 17,00,08,00             ;Jan
                NV0Byte 17,30,07,30             ;Feb
                NV0Byte 18,00,07,00             ;Mar
                NV0Byte 18,30,07,00             ;Apr
                NV0Byte 19,00,06,30             ;May
                NV0Byte 19,00,06,00             ;Jun
                NV0Byte 20,00,06,00             ;Jul
                NV0Byte 20,00,05,30             ;Aug
                NV0Byte 19,00,06,00             ;Sep
                NV0Byte 18,00,06,30             ;Oct
                NV0Byte 17,30,07,00             ;Nov
                NV0Byte 17,00,07,30             ;Dec