what is the difference between DateTime and LocalTime

Hi , I'm using GSV and SSV instruction set and read dates but I see there are 2 attributes for the wallclock object.

DateTime and LocalTime.

What is the difference?

Regards

I believe the DateTime uses UTC time, and LocalTime will use the timezone and daylight savings if they are configured.

Thanks

Full answer.....


The DateTime values are what the WallTimeClock is running on. The RTC runs on UTC only, and has no concept of DST (Daylight Savings Time). Rockwell sells their products globally, and to deal with DST internationally would be a nightmare. Google DST and you will see what I mean, many countries have different ideas.....


The LocalDateTime is an adjusted time, dependent upon the values you set (using SSV) in DST_Offset. This is a value (in minutes) that you can define, and adjusts the DateTime value by the number of minutes you program it to.

Also bear in mind that the PLCs clock will not "apply" DST to the Local Date/Time automatically, you have to tell it, programatically, when to do so, dependent on the dates involved.

I have a working solution, UK based, that keeps the operators view of the DST adjusted clock correct. You may be able to use this in your application. PM me if you are interested.