Damica

Timed Interrupt (STI)

9 posts in this topic

If I understand the STI is just an Interrupt that will run every 32756 ms or 32.75 seconds. Is there any way this can be increase to around 10 minutes? I don't want to use a timer because the rest of the program will not be running while the timer is counting. Thanks

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I think my first question is being 10 minutes between interrupts, is there a reason it needs to be an STI as opposed to using a regular timer in the ladder program to do the task.

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Maybe I don't know exactly how a timer functions? Can you explain! If I use a timer in a subroutine (10 minute timer ) and I am going to have an event on the DN bit. What will happen when the first subroutine gets done and the (Timer.DN bit is not true yet) will that timers DN bit still activate or become true? Also that DN bit is going to call another subroutine. How many timers can I have going at the same time. I'm thinking I will need 9. Thanks for your help

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Attached is a basic example of a timer that will execute a routine every 10 minutes. Have a look at it and see if it makes sense.

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Assuming thaat this is a ladder logic program, the program scan does not halt while a timer is active. If the timer is in a subroutine it would have to be continously scanned (or called) at least until the timer has finished. It's like startting a timer with an alarm. You can do other things until the alarm alerts you to do the things intended.

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Thanks for both reply's. Industrial Sorcerer, I can't find the attachment, I'm new here so may not know how get attachments. I want to see, all information is helpful.

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Probably because I forgot to post it. See attached 10minutetimerroutine.RSS

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Would you be kind enough to look over this file and tell me if I working in the right direction. I am new, I know it's not labeled well yet but I will get better as I learn. Thanks, I do appreciate all the help. EMAIL_Sample.RSS

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The STI can be configured to interrupt the scan using the STE and STD instructions. In this way you could create zones all over your subroutines that would interrupt the main scan. These STI routines are time based rather than event based. The other useful thing about the STI is that you can configure the time interval that the STI looks at the selected zone. This would be useful if you had to capture information/make calculations etc. If you want more than one subroutine file to be scanned you can use the STS instruction to feed info to S:30 and S:31 to input the interval and the file number. This instruction can add to the total scan time depending on what you set the interval to and there is some latency between the STI timeout and the start of the interrupt routine and also is dependent on what processor you are running.

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