28 | C1508M-A (02/01)
For example, if system time in step 7 had read 2:02.30 (2 minutes and 30 seconds after
2 PM) at the time RTC time read 2 PM, then we know that system time, over the next 24
hours, must be slowed by 2 minutes and 30 seconds to synchronize system and RTC
time. To accomplish that, enter a negative (-) sign in front of the time differential that you
enter. In this case, that would be:
-02 : 30 . 00
This subtracts 2 minutes, 30 seconds from system time over the next 24 hour time period
so that when you compare system time with RTC time again, they should theoretically be
equal. Be sure to use the above format.
If you wish to refine the adjustments to your original effort, you can quit to the DOS screen,
set RTC and system time to be equal to each other, invoke the executable for the diagnostic
screen from the C:\9740 directory, and then use your original time adjustment (in our example
-02 : 30 . 00) as a basis for entering a new time adjustment that differs incrementally from
the original. That might work based on something like the following reasoning: Say that five
days (five 24 hour periods of time) have passed and you again check system time against
RTC time. This time you discover that over the five-day period, you are running 10 seconds
slow, or, on average, 2 seconds slower for each 24 hours of elapsed time. This time you
must change the original time adjustment by ADDING 2 seconds to the original, NEGA-
TIVE time adjustment.
In order to factor in the new adjustment, you should perform the following steps again, pref-
erably, just before the top of the hour:
1. Quit the diagnostic and revert to the DOS screen using Ctrl + Q.
2. Invoke the DOS line command–TIME–to bring up current system time.
3. Pre-enter your system time to read top of the hour time. For our example, continue to use
2 PM as RTC time, so at the NEW TIME prompt on the DOS screen, you would enter:
2:00:00.0p
When RTC time reaches 2 PM, press the ENTER key, proceed to the C:\9740 direc-
tory and invoke the system executable, which includes your global configuration file-
name as an argument, (CM9740 TEST, for example) and boot to the diagnostic screen.
4. At the diagnostic screen, issue the ALT + L key combination.
5. On the command line, the following should appear:
Last Adj -2 : 30 . 0 Total -2: 30 . 0
6. Now enter in your refined time adjustment as a change to the last adjustment shown
on the screen. In this example, you would enter the following:
-2 : 28 .0
that is, [(-2 : 30 . 0 ) + (00 : 02 . 0)] = -2 : 28 .0
7. After pressing the ENTER key, the System box will read
Last Time Adj -2:28.0 Total -4:58.0
Subsequent adjustments, if necessary, can be made using the previous discussion as
a guide.
7.2.2 General Remarks Regarding System Time Adjustment
We have just discussed setting and adjusting system time for single-node operation. How is
this accomplished for other configurations?
For a hot-switch configured node, the CC1s are synchronized through the intermediation of
the hot switch. Setting or adjusting time on one CC1 will, when it is brought back online and
put in synchronous mode, cause the time adjustment to be synchronized for both CC1s.
