changing summer/winter time whit s7 300 (CPU 314)

hello everyone,

I have a problem, i searching for a way to change the summer winter time whit a s7 300 plc whit a cpu 314. can anyone help me????

In hope to hear anything about this soon, i thank everyone.

Hi

There are two System Functions SFC0 and SFC1 which set and read respectively the real-time clock in the S7-300 CPU.

How about calling the READ_CLK SFC1 once every day (stick the call in time-of-day interrupt OB10 set for daily execution at an appropriate time), and checking whether the date and time time have passed the key points for switching between winter & summer time. If so, call the SET_CLK SFC0 with a value either 1 hour more or 1 hour less than you have just read according to the month.

This should require OB10, 1 call each to SFC0 and SFC1, and some comparison code to check on the result of reading the clock.

Good luck.

Ken

I have not yet implemented this but there is a block FB61 that works with UDT60 to change from winter to summer. Look in the step 7 library files.

If you have an s7300 PLC with firmware V3.0 or later then the hardware clock settings include winter/summer time.

John,

What about the size of these blocks? What on Earth are they doing!

FB60 itself is 5740 bytes, and it calls (wait for it!) FCs 1,3,7,12,18,23 and 35 from the IEC Library. FC1 and FC35 alone are over 1500 bytes each, the others are all around the 300-500 byte mark. That's getting on for 10Kbytes, just to change a clock. Ye Gods, and little fishes - there might just be room left for a small program beside that!

Ken

Frank,

do in the PLC program what you do when you're adjusting your wall clock: read the time, set the hour part 1 higher or 1 lower and set the time. Shouldn't be too hard, even for you.

See you tomorrow in class!

Your teacher,

jvdcande said:

Frank,
...
See you tomorrow in class!

Your teacher,

Click to expand...

Ooooooo...BUSTED!

Ooooooo...BUSTED!

Click to expand...

I have mentioned it before: it had to happen someday.

Regards,

Be very careful of a possible trap when going from Summer to Winter time. Think about what you would do but also remember that the PLC judgement is tied to the code and to the CURRENT value of the clock. I hope that's not too much help.

I hope that's not too much help.

Click to expand...

Nope. That's one of the hints he would get from me, would he come for help in class.

Kind regards,

thanks

hello everyone,

I want to thank all the persons who gave me an answer.
Jean-Pierre, i want to thank you also and thell you that the system woks.

Regards,