SFC1 "READ_CLK" returning value of zero

Hello,

I am trying to setup code to compare specific times of day to the Date and Time of the PLC.

I use SFC1 "READ_CLK" function and input it to the DT_TOD function to get the "Time od Day" then move this to a REAL data type in my DB to compare.

My problem is I am not getting a value from the READ_CLK function, it remains zero all the time.

I am using Step7 5.5 SP04 with a CPU 315-2 DP PLC.

See attached code with monitor on.

Any suggestions    

Hi 

Simatic manager V5.5 can't show the values of date and time, if you wanna see the current values directly in Simatic manager it's only possible in TIA portal, or you can check the values in WinCC.

Best Regards

Hi,

Did you made the good format declaration in your DB?

If you want to store a TOD Format you must declare as TOD the place where this TOD data will stored and no other format.

You can also use a pointer and directly send the DT format from FC1 to the DB without using DT_TOD function then recover the TOD directly from your DB!

For information as i know DT and TOD is in BCD consequently the value showed on the DB is not like an integer if it's 10 o'Clock you will not certainly see 10 but the BCD value of 10.

Hope this help you, i don't know if it's possible to see directly the value on your step7 version but you can also try to use a VAR Table or see directly inside the DB!

regards

Issue Resolved.

I reloaded the DB, FC and OB1 and I can see the clock values now.

Thanks for the suggestions.

Hi!

Can you connect current time that is internal variable in your code (output of SFC1) in Time_And_Date format to Data block? appreciate if you can share it in print screen.