S7 Day of Week from SFC1 and FC7

Hello all, I am having troubel getting the day of week data out of the SFC1 and FC7 functions. I am able to get a number from FC7 but the number continuously counts up from -32000 to 32000 and then repeats. It takes only about 60 seconds for the cycle to repeat.

However, when I go into the simulator it workd fine. But is does not work in the actual plc. I believe I should get an integer between 1 and 7 depending of whick day of the week it is.

I have read though numerous posts on this subject but none of them concern the problem I am having.

Any ideas on why this is happenning, thanks, mrt19

The output from FC7 should give you an integer in the range 1 to 7; with 1 being Sunday, 2 being Monday etc up to 7 = Saturday.

What else have you in the PLC?
Are you over writing the same data area that you have assigned the RET_VAL of FC7 elswhere in your program?

Try this - example is inside a FB

CALL "READ_CLK"
RET_VAL:=#iResultSfc1 // Temp data type = Int
CDT :=#dtReturned_time //Static data type Date_and_time

LAR1 P##dtReturned_time // Load Address register 1 with D+T

L B [AR1,P#7.0] // Offset to day area
BTI // convert BCD to integer
T #iWeekday // transfer to Static integer Weekday

No FC7 needed

As Moggie says 1 being Sunday, 2 being Monday etc up to 7 = Saturday

Note: this will not work if the FB is used in a multiple instance The day of the week is in the lower byte of byte 7. See code below:

Modified as LD rightly says Byte 7 needs work prior to transfer