im looking for a program that works on a slc500 for daylight savings time you can e-mail it to [email protected] thanks
daylight savings time
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Mickey
Lifetime Supporting Member
Steve Bailey
Lifetime Supporting Member + Moderator
Here's a quick and dirty generic approach for the United States that does not involve resetting the PLC's RTC.
Use Actual_Hour instead of RTC_Hour in your program. The 'DST' bit must be retentive.
Month=April DOW=Sunday DOM<8 Hour=2 DST
----] [---------] [--------] [----] [-----(S)-
Month=Oct DOW=Sunday DOM>24 Hour=2 DST
----] [---------] [--------] [----] [-----(R)-
RTC _____________
--] [-------------| ADD |
| RTC_Hour |
| 1 |
| Actual_Hour |
|_____________|
RTC _____________
--] [-------------| ADD |
| RTC_Hour |
| 0 |
| Actual_Hour |
|_____________|
Use Actual_Hour instead of RTC_Hour in your program. The 'DST' bit must be retentive.
Last edited:
bernie_carlton
Lifetime Supporting Member + Moderator
I assume you meant DST and NOT DST as the two enabling contacts to your ADD blocks. What happens if the PLC isn't turned on at the particular changeover hours?
PhilipW
Member
There is also a version for the SLC500 that I posted on the downloads section of this site.
It calculates on an absolute basis, ie it does not require the PLC to be running at the time of the changeover.
It calculates on an absolute basis, ie it does not require the PLC to be running at the time of the changeover.
Steve Bailey
Lifetime Supporting Member + Moderator
You're right Bernie. I was a little too quick and got my face dirty.
rdrast
Lifetime Supporting Member
But what does one do in the event of a 'leap-second' ? didn't we add one this year?
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