Automatic DST time change is enabled when shipped from the factory. Follow the instructions below to disable it.
1. Enter the Advanced Programming Mode: 80
2. Enter the Advanced Programming Security Code: 4150
3. Enter the address (from the Address Table) for the Auto DST function: 1017
4. Enter a value of 0 to disable this function: 0 (or enter 1 to enable this function)
5. Press the # key to write this value (and increment to the next address in memory)
6. Press the ❊ key to exit programming mode and return to operating mode
Automatic DST adjusts the clock as required. No other changes are made in the system. All date/time triggers occur
according to the values that are programmed. Trigger times are compared against the DST adjusted clock.
6.4.5 Clock Calibration
The RFC-1 real time clock is based in the main processor. Like any processor-based clock, its accuracy is subject to
the manufacturing tolerance of the components. It is normal for the time to drift a little over long time periods.
6.4.5.1 Automatic Calibration
The RFC-1 attempts to synchronize the real time clock to the incoming AC power supply. This typically offers very
good long-term stability. This feature is enabled by default and operates without user intervention when the RFC-1 is
powered from either a 50 Hz or 60 Hz AC main power supply.
Automatic clock calibration requires hardware that was added to RFC-1 systems in mid-2003. Early RFC-1 versions
do not have the hardware necessary to support this feature.
6.4.6.2 Manual Calibration
The RFC-1 clock can be calibrated manually. This can be used to improve the accuracy of RFC-1 versions that do
not have the AC sample hardware or that operate from DC supplies. The RAK-1 powers the RFC-1 from an internal
DC supply so it also benefits from this feature.
Manual clock adjustment trims the speed of the internal clock to compensate for variances in timing components in
the RFC-1. Each step changes the speed by one-half second over a 24-hour period. The AC sync feature is
automatically disabled when a manual clock calibration adjustment is made.
To calibrate the RFC-1 clock, set the RFC-1 clock to a known accurate source. Let it run for several days until the
time drifts by more than a minute. Divide the number of minutes of drift by the number of days to determine how
many seconds the clock drifts per day. Seconds of drift per day = (minutes of drift * 60) / number of days.
Look in the table below for the number that is closest to the clock drift. If the clock runs slow, look for a negative
number. If the clock runs fast, look for a positive number. Each setting in the table is represented by a pair of values:
V1-V2. Program V1 at memory address 1018 and program V2 at address 1019.
The clock loses time when it runs to slow. Suppose the clock is set to a known accurate time. Six days later at 6:00
pm the RFC-1 clock is checked. Instead of 6:00 pm it reads 5:58 pm. It is running too slow and has lost 2 minutes.
Negative numbers in the table below make the clock run faster. The drift is (-1) * (2 * 60) / 6 = -20 seconds/day.
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