Siemens SIMATIC PCS 7 Function Manual page 237

Local time
The local time is displayed at the QLOT_DT and QLOT_DTB outputs of the block. The local
time is the UTC time adjusted for daylight saving time and time zone.
The divergence between local time and UTC time due to the time zone is specified at the
"LOT_DEV" input (in minutes, +/- 720). The default value of the input is "60". This represents
the time zone "UTC + 01:00" (Amsterdam, Berlin, Bern, etc.).
The divergence due to daylight saving time is specified at the "DST_DEV" input (in minutes,
+/- 120). The default value of the input is "60".
Switch to daylight saving time
For Europe, the clock change time is calculated in the block. The time of the switch to daylight
saving time is the last weekend (Sat/Sun) in March; the clock is set forward at 2:00 am on
Sunday. The end of daylight saving time is the last weekend (Sat/Sun) in October; the clock
is set back at 3:00 am on Sunday.
For regions outside Europe, the clock change time can be set at the "DST_ON" input. Bit 0 of
the mode word is used for selection.
Modified Julian date
The block calculates the modified Julian date on the basis of the UTC time and displays it at
the "QMJD" output.
The resolution of the value is around 15 minutes. Higher resolution is available at the
"QMJD_DAY" and "QMJD_TOD" outputs. "QMJD_DAY" contains the integer places and the
"QMJD_TOD" output the decimal places of the modified Julian date
Date of birth (DOB) and best before date (BBD)
The date of birth and best before data are provided at the block outputs either cyclically or on
request, depending on the mode. Bit 4 (TRIGGER) of the mode word is used to set the mode.
With triggered provision of the DOB and BBD, a positive edge at the "GENERATE" input
generates the date of birth and best before date and outputs these dates at the QDOB_DT/
QDOB_DTB and QBBD_DT/QBBD_DTB outputs for further processing. The provision of the
data is indicated at the "PROVIDED" output ("PROVIDED" = 1). The "PROVIDED" output is
rest when the trigger is removed.
Provision is also indicated at the "PROVIDED" output with cyclic provision of the DOB and
BBD.
The shelf life is specified at the SL_HOUR and SL_DAY inputs (SL = Shelf Life); the two values
are added together.
The setting range for "SL_HOUR" is between 0 and 9999 hours and the range for "SL_DAY"
between 0 and 6000 days.
Advanced Process Functions (APF)
Function Manual, 07/2016, A5E38719883-AA
Best before / UTC time supply
9.1 FB_BBD
237