Time Display Format; Date Display Format; Auto Change For Daylight Savings Time; Meter Type For Clock Synchronization - Omega Engineering PTC900 User Manual

TIME DISPLAY FORMAT

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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.

DATE DISPLAY FORMAT

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.

AUTO CHANGE FOR DAYLIGHT SAVINGS TIME

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).

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 (
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.
CALIBRATE REAL-TIME CLOCK
* NOTE: DO NOT ADJUST TRIM CAP ON RTC CARD!
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.
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). Once every
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.
Selecting for the parameter displays 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.
IF RTC CLOCK GAINED TIME:
USE VALUE FROM THIS TABLE
SECONDS ENTER THIS
GAINED IN
30 DAYS
5
11
16
21
26
32
37
42
47
53
58
63
69
74
79
84
IF RTC CLOCK LOST TIME:
USE VALUE FROM THIS TABLE
SECONDS ENTER THIS
LOST IN 30 OFFSET
DAYS
11
21
32
42
53
63
74
84
95
105
116
127
137
148
158
169
25
to
sub-menu where the
SECONDS ENTER THIS
OFFSET GAINED IN OFFSET
VALUE 30 DAYS VALUE
01 90 17
02 95 18
03 100 19
04 105 20
05 111 21
06 116 22
07 121 23
08 127 24
09 132 25
10 137 26
11 142 27
12 148 28
13 153 29
14 158 30
15 163 31
16
SECONDS ENTER THIS
LOST IN 30 OFFSET
VALUE DAYS VALUE
33 179 49
34 190 50
35 200 51
36 211 52
37 221 53
38 232 54
39 243 55
40 253 56
41 264 57
42 274 58
43 285 59
44 295 60
45 306 61
46 316 62
47 327 63
48