Calculate differens in second between two times.

Hi,

I need to create a logic who calculate how many seconds between current time and 1970 00:00.

I need these for time sync between a 400 PLC and a modbus slave (Autronica Fire Central).

Somebody who has done someting similar?

My plan was to establish a code who calculate how many seconds there are between current time and 1970 00:00 and these results shall be sent over the modbus slave.

Please see documentation from the Central.

http://www.ucolick.org/~sla/leapsecs/epochtime.html

Good luck

Thank you :)

I have found a bachelor thesis also,
https://publications.theseus.fi/bitstream/handle/10024/60951/Wargh_Joakim.pdf?sequence=1

I have tried to make the same FC he make in the appendix to the thesis, I started with alot of errors,
now I have some left, I have problem to understand, somebody have time to take a look?
I haven`t used SCL before...

Please see attached source file.

Your help is pressured.

Well,

your screen shots and the source file don't match. What's up?

BTW, in the source file all type cast functions are missing underscores in their names.

I.e. "INT TO DINT" should be "INT_TO_DINT" and so on.

BTW2, have look here and here.

BTW3, despite we are talking in Step7 conference, from the screen shots it can be seen that you use TIA. Moreover you write software for the 1500 possibly. Why don't you use simplest way DTL_TO_LDT ? Unless you write it for the 1200...

Thank you all for feedback!

Piotr.M

Function which uses tricks from Jaceks' links (thanks!) attached.

The pre-condition for long formula where it uses year-1900 is embedded in formula itself

Comprehensive arguments check is applied too

Function returns:

1. ENO=FALSE and RET_VAL=0 when any argument is not good

2. ENO=TRUE and RET_VAL=seconds since 1970/01/01, 00:00hrs (as double int) when all arguments are good.

NOTE: YEAR is limited to 2038 to prevent arithmetic overflow.

When higher years are required 64-bit Int data type is required (you will need create your own library

or use 64-bit REAL - library can be found here: https://support.industry.siemens.com/tf/gb/en/posts/64-bit-real-support-for-s7-300-plcs/121779/?page=0&pageSize=10&zone=Extranet)

.

 Thank you for your feedback.

Do you have a example how I can read system clock from CPU and divided it up into INT`s?
Your FC need inputs in INTS for Year, Moths, Days, Minute, Seconds?

Piotr.M

Yes, My FC needs input of time in ints (year, month, day, hh, mm. seconds assumed 0).

my function synchronizes PLC with SCADA which gives time as set of integers.

I have added an example how to split date & time (which you can read from PLC using the SFC)

to individual elements in the printout attached to previous post)

 Thank you for your quick feedback.

I think there are a bug in the example you made in the last NW?

Because the I for year is coming out as 1916 (Cpu time is 2016).
I can see you are +I  1900, I changed from 1900 to 2000.

So

  L     LB     0                    // store in local bit [will be from 0]
      BTI  
      L     20000
      +I 

Then the output for I year was 2016.

Have I done it correct?

Now I have only one question left...

The modbus slave need to recive the time and date since 1970 in two words,
MSB and LSB word.
Can you give me a example how I convert the DINT output from your FC to two words MSB and LSB?

Thank you... I ow you !

Copy / past from modbus documentation:
(These two registers simply store the Unix time to be transferred, that
is, seconds since Jan 1 1970, 00:00.
Note that Holding Register 1 needs to be zero when writing to register
2 and 3.
Register 2 is the Most significant half of the 32 bit value.)

Thank you so much.