Maple Systems OIT Family - Manual (Page 101)

2. In the Download Clock To PLC group box, select the PLC address to download to.
3. In the Download group box:
• If you want the OIT to download the time to the PLC, select the Time check box.
• If you want the OIT to download the date to the PLC, select the Date check box.
4. Choose the Done button to return to the OITware-200 main screen.
The clock’s time will be sent to one 16-bit PLC register. The hour (HH) of the day (in 24
hour format) is stored in the eight most significant bits in BCD format. The minutes
(MM) of the hour is stored in the eight least significant bits in BCD format. For example,
if the current time is 2:35 p.m., then the OIT would send to the PLC register the value
1435 (HHMM) in BCD format.
The clock’s date is sent to two 16-bit PLC registers. The first register stores the month
and day of the month. The second register stores the day of the week and the year. All
values are in BCD format. For the first register, the eight most significant bits are used
for the month (MM). The eight least significant bits are used for the day of the month
(DD). For the second register, the eight most significant bits are used for the day of the
week (DY). The day of the week would be represented with a number from 1-7 with the
number 1 representing SUNDAY, the number 2 representing MONDAY, etc. The eight
least significant bits are used for the year (YY). For example, if the date of the clock were
Wednesday, September 13, 1995, then the OIT would send to the first PLC register the
value 0913 (MMDD) in BCD format and the second PLC register the value 0495
(DYYY) in BCD format. If both time and date are checked, then three PLC registers are
used with the first register used for time and the other two registers used for date.
Using the Real-Time Clock 101
1010-0099, Rev. 07