9440300990 25-1
DECS-250 Timekeeping
25 • Timekeeping
The DECS-250 clock is used by the logging functions to timestamp events. DECS-250 timekeeping can
be self-managed by the internal clock or coordinated with an external source through a network or IRIG
device.
BESTCOMSPlus
®
Timekeeping settings are shown in Figure 25-1.
BESTCOMSPlus Navigation Path: Settings Explorer, General Settings, Clock Setup
HMI Navigation Path: Settings, General Settings, Clock Setup
Time and Date Format
Clock display settings enable you to configure the time and date reported by the DECS-250 to match the
conventions used in your organization/facility. The reported time can be configured for either the 12- or
24-hour format with the Time Format setting. The Date Format setting
A
configures the reported date for
one of three available formats: MM-DD-YYYY, DD-MM-YYYY, or YYYY-MM-DD.
Daylight Saving Time Adjustments
The DECS-250 can automatically compensate for the start and end of daylight saving time (DST) on a
fixed- or floating-date basis. A fixed-date, for example, is March 2, and an example of a floating-date is,
“Second Sunday of March”. DST compensation can be made in respect to your local time or coordinated
universal time (UTC). DST start and end points are fully configurable and include a bias adjustment.
Network Time Protocol (NTP)
When connected to an Ethernet network, the DECS-250 can use NTP to assure accurate, synchronized
timekeeping. By synchronizing with a radio, atomic, or other clock located on the internet/intranet, each
DECS-250 maintains accurate timekeeping that is coordinated with the time source.
NTP Settings
NTP is enabled in the DECS-250 by entering the internet protocol (IP) address of the network timeserver
in the four decimal-separated fields of the NTP Address setting. Time zone offset settings provide the
necessary offset from the coordinated universal time (UTC) standard. Central standard time is six hours
and zero minutes behind (–6, 0) UTC and is the default setting.
The Time Priority Setup must be used to enable a connected time source. When multiple time sources
are connected, the Time Priority Setup can be used to rank the sources according to their priority.
IRIG
When the IRIG source is enabled, through the Time Priority Setup, it begins synchronizing the DECS-250
internal clock with the time code signal.
Some older IRIG receivers may use a time code signal compatible with IRIG standard 200-98, format
B002, which does not contain year information. To use this standard, select the IRIG without Year radio
button in the IRIG Decoding box. Year information is stored in nonvolatile memory so the year is retained
during a control power interruption.
The IRIG input accepts a demodulated (dc level-shifted) signal. For proper recognition, the applied IRIG
signal must have a logic high level of no less than 3.5 Vdc and a logic low level that is no higher than 0.5
Vdc. The input signal voltage range is –10 Vdc to +10 Vdc. Input resistance is nonlinear and
approximately 4 kΩ at 3.5 Vdc and 3 kΩ at 20 Vdc. IRIG signal connections are made at terminals IRIG+
and IRIG– which are located on the right side panel.
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