25
TIME DISPLAY FORMAT
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DATE DISPLAY FORMAT
AUTO CHANGE FOR DAYLIGHT SAVINGS TIME
Select the format in which the Real-Time Clock Time will be displayed. The
format selections depict the
range
for the RTC Time display, and DO NOT
represent the
current
RTC Time. When the meter is operating in the Display
Mode, the RTC Time display is shown with no annunciator.
Selecting
allows the meter to automatically adjust the RTC Time for
Daylight Savings Time. (Adjustment dates are U.S.A. standard only.) Avoid
setpoints that occur during adjustment (Sundays 1 to 3 AM).
Select the format in which the Real-Time Clock Date will be displayed. The
format selections depict the
range
for the RTC Date display, and DO NOT
represent the
current
RTC Date. When the meter is operating in the Display
Mode, the RTC Date display is indicated by the DAT annunciator.
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METER TYPE FOR CLOCK SYNCHRONIZATION
Time synchronization between multiple PTC901 meters can be
accomplished through a hardware interface on the Real-Time Clock option
card. This RS485 type interface allows connection of up to 32 PTC901 meters
in a two-wire multidrop network, at distances up to 4000 ft. (See Section 4.6,
Real-Time Clock Wiring).
In a Synchronization network, one PTC901 meter is programmed as the Host
(
), while all other meters are programmed as Slaves (
). Once every
hour (at 30 min. past the hour), the Host meter outputs a time synchronization
pulse onto the network. Upon receiving the synchronization pulse, each Slave
meter automatically adjusts the Minutes and Seconds of its RTC Time setting to
synchronize with the Host.
Synchronization, using the Real-Time Clock Wiring,
adjusts the Minutes and Seconds only, and does
not
change the Hours, AM/PM,
Day or Date settings in the Slave meter's RTC.
Full-time synchronization (hours, minutes and seconds) is possible for
PAXCKs that are connected in an RS485 network (RS485 Serial Option cards
required). In this configuration, one meter is designated as the Serial RTC
Master by setting the meter's address as 98 or 99 (see Serial Real-time Clock
Addressing in Master Module 7). Every hour (at 30 min past the hour), the
Serial RTC Master / Host will transmit the full time (Hours, minutes, seconds)
to all meters through the RS485 serial card wiring network. The time, date, or
day will also be transmitted and updated in the Slaves when changed in the
programming of the Serial RTC Master. Only one meter should be configured
as Master and that meter should also be configured as the Host.
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CALIBRATE REAL-TIME CLOCK
The Real-Time Clock circuit uses a crystal controlled oscillator for high
accuracy timekeeping. The oscillator is factory calibrated* and optimized for
25°C ambient temperature operation. Since the PTC901 is designed to operate
over a wide temperature range, and since the accuracy of a crystal oscillator
varies with ambient temperature, some drift in the RTC time may be observed
over an extended period. This is primarily seen in high or low temperature
installations. To compensate for the wide operating temperature range, a
calibration or “Offset” value can be entered, which effectively slows down or
speeds up the clock to maintain accurate timekeeping.
*
NOTE: DO NOT ADJUST TRIM CAP ON RTC CARD!
12-59p
12-59
23-59
+B/
sun-31
IF RTC CLOCK GAINED TIME:
USE VALUE FROM THIS TABLE
31
163
30
158
29
153
28
148
27
142
26
137
25
132
24
21
111
127
20
105
23
19
100
121
18
95
22
17
90
ENTER THIS
OFFSET
VALUE
116
SECONDS
GAINED IN
30 DAYS
16
84
15
79
14
74
13
69
12
63
11
58
10
53
09
47
08
05
26
42
04
21
07
03
16
37
02
11
06
01
5
ENTER THIS
OFFSET
VALUE
32
SECONDS
GAINED IN
30 DAYS
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Selecting
for the
parameter displays the
sub-menu where the
present Offset value can be viewed or changed. The tables below show the
value to enter, given the amount of time gained or lost in a 30-day period.
Values 00 and 32 provide no Offset, and are not shown in the tables.
to
IF RTC CLOCK LOST TIME:
USE VALUE FROM THIS TABLE
63
327
62
316
61
306
60
295
59
285
58
274
57
264
56
53
221
253
52
211
55
51
200
243
50
190
54
49
179
ENTER THIS
OFFSET
VALUE
232
SECONDS
LOST IN 30
DAYS
48
169
47
158
46
148
45
137
44
127
43
116
42
105
41
95
40
37
53
84
36
42
39
35
32
74
34
21
38
33
11
ENTER THIS
OFFSET
VALUE
63
SECONDS
LOST IN 30
DAYS
To calibrate the RTC, install the meter in its normal operating environment,
and set the time based on a known accurate reference (such as the WWV
broadcast or the Atomic Clock reference which is available via the internet).
After 30 days of normal operation, compare the RTC time to the reference, and
note the amount of time gained or lost. Refer to the tables on the next page for
the proper Offset value to enter, given the amount of time drift observed.
