FB for Start of day

[huynt]

Dear all.
We want to use S7-300 for Truckloading system. I have problem with Start of date. Do you know FB or method to detect start of date. We use this for caculate volumn of oil in one day. About 18 h PM, power of PLC is off, and about 7 h AM.
Help me!

[SimonGoldsworthy]

Do you mean "how do I detect the time of day that the plc was started" ?
If so, put some code in OB100 to read the time and date from its temp data area (called OB100_DATE_TIME) and then store this in a DB.

[huynt]

No, When PLC power on, it dectect new date, It will set a bit, when power on, date same previous power on, this bit cannot set.We use this bit for caculate volumn tranfer in one day.

Thanks
huynt