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implementation of time triggered events

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imagine ive got a schedule to turn on and off many leds at a givent time of day as attached. (col 3=on  time, col 4 = off time).

whats the best way to implement this?

an event case firing events at given timestamps? (ive already converted strings to timestamps)

2 event structures (one for the on and one for the off times)?

a while loop with 1s period?

a timed loop? 


ps. this is going to be part of a larger project im working on. actually some serial bytes are going to be sent at every given time.

obviously i could go with a while loop ticking every second and comparing current time with my on and off timestamps, but  i can see its a waste of resources.


any ideas? thank you in advance.

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Message 1 of 10

One thing you could implement is a "Scheduler".  Suppose you need to turn things on and off with a time accuracy and precision of 1 second.  You could create a "Schedule", an Array of Clusters that contain a Time and an Action (which could be a Boolean, On/Off, and an identifier to say which control to turn on or off).  You have one routine that adds new Events to the Schedule, another that acts like a Clock, firing once/second and seeing if anything is due to be Scheduled Now.  If no, then you "go back to sleep", otherwise handle whatever needs to be scheduled.  I recommend that you do this in a parallel process so that the "clock" runs independently from the process being scheduled.


Bob Schor

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Message 2 of 10

i've already got a kind of scheduler. my on off timestamps are stored in a multicolumn listbox for each day of the week. i just need to generate an event at given times of day without using a while loop comparing every sec my system time with the given timestamps. 


wasting resources if you think that in a day i could have one or two timestamps.

any help on how to implement that?

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Message 3 of 10

came with a solution. i calculate the time remaining to nexr event and feed it to a timeout event structure. works well but im having issues when i have the same timestamp for 2 items. works if they have 1sec difference.


but given that i need to send & receive serial commands at 9600baud instead of turning on off leds i would need some sort of queue for the commands to be sent that have the same timestamps (both on & off).


any ideas? thank you.

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Message 4 of 10

I don't have LabVIEW 2016, so I can't look at your vi,

but be aware that the Event Timeout is not a reliable

timing method.


Any Event that occurs (like a button push or user Event) will reset the timer.


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Message 5 of 10

that event structure will only have the timeout event. 

i uploeaded a sc. the false case only increases the index. 


any other ways to generate events at given timestamps?

im new to labview so im short of ideas. thank you.

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Message 6 of 10

I don't know how "new" you are to labVIEW - your block diagram is very

clean and organized - better than I've seen from some experienced people. Kudos.


Bob_Schor gave some very good advice earlier. I would like to add a bit to his mention

of using an Array of Clusters. If each cluster has a timestamp and an an array of

actions, you can handle those occasions where multiple events need to be performed

at the same time. Use a For Loop to process the actions.


I haven't been able to think of a way to avoid polling the timestamps for the next action(s)

but 1 one second interval should not cause any issues. I think you can do without the

Event structure.


For sending the data to your serial device, I would send the data (or request) to a

consumer loop using a queue.


You haven't said how accurate the timing needs to be. This would be useful to know.



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Message 7 of 10

thanks for that. like to keep things nice and clean. been using since august.


as for timing accuracy. on a given timestamp i should send a serial command and get a response from a plc. 


so two items with the same timestamp should be sent "simultaneously". obviously send second command after ive got the first response. so a queue should be useful here as you stated. one sec of a difference between the to commands is more than enough for me.

keep in mind that my "list" could have up to 20~30 items so 40-60 timestamps. so ill need to poll all of them each sec. 


as for the array of clusters. if i got it right. lets say ive got 20 items. so 40 timestamps.

you mean i should create 40 clusters with a timestamp and the command to be sent. then feed them in an array and poll them each sec? obviously will be handy to sort the array by the timestamps.

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Message 8 of 10
Accepted by topic author afetsis

Yes, I would assemble the array in timestamp order.

Then you only have to check one array entry.

When you get a match, process it and increment the array.

Here is a simplified array of clusters based on your earlier posting:

Event triggers.png

Notice how multiple concurrent actions are handled (first element). The example shows

an array of strings for the action, but it could be a cluster of items if that is useful.

Be sure to name the cluster items and "Type-Define" your clusters.


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Message 9 of 10

done. my timestamps with the respective serial commads. Smiley Happy

thank you all for your help.

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Message 10 of 10