User`s guide

Data Storage Configuration
Storage Conventions
Release E UMC800 Control Builder User’s Guide 185
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Storage Conventions
Storage modes
Trends, Point Log, and Alarms/Events can be stored in Continuous or Batch modes. In addition, Point Log
can be stored in On Command mode. See Table 47 for Storage Modes descriptions.
Table 47 Storage modes
Mode Description
Off No data will be collected
Continuous Data is sampled at the storage interval
Batch Data is sampled at the storage interval, but also a Batch Enable Signal separates the
sampled data into numbered batches. Batch #1 begins when the Batch Enable
Signal turns on, and ends when the signal turns off. Batch #2 begins when the Batch
Enable Signal turns on, and ends when the signal turns off, etc. No batch mode data
is collected while the Batch Enable Signal is off. The Batch Enable Signal does not
affect data being stored as Continuous or On Command.
On Command Point Log data is sampled on each off-to-on transition of the Point Log Enable Signal.
Storage intervals
When data storage is enabled, samples are taken at regular intervals known as the storage intervals. These
intervals can be from a few seconds to 30 minutes. Each data type has its own storage interval. For
example:
Trends can be stored using one interval (like 5 seconds),
Point Log using another interval (like 10 per day), and
Alarms/Events (stored as they occur).
Or, they can all use the same interval. It depends on how data storage has been configured.
In Continuous and Batch modes, the storage interval determines how often data is sampled and stored:
• For trends and alarms/events, data is first sampled when storage is enabled and again at equally spaced
intervals thereafter. For example, if trend storage is enabled at 2:03 p.m. and the interval is 10 minutes,
trend storage occurs at 2:03, 2:13, 2:23, etc. until storage is disabled.
• For Point Log, data is first sampled after storage is enabled but not until the programmed Start Time.
Data is sampled at equally spaced intervals after the Start Time. For example, suppose the Start Time is
3:00 p.m. and the storage interval is 10 minutes. If storage is enabled at 2:03 p.m., the first sample will
occur at 3:00 and every 10 minutes thereafter. If storage is disabled at 3:35 and enabled at 3:42, storage
will resume at 3:50. Notice that the interval is synchonized to the Start Time.
• Alarm/Events are logged on occurrence with time and date (No interval)
In On Command mode for Point Log, there is no storage interval or Start Time. A single sample of Point
Log data is taken when the Point Log Enable changes from off (disable) to on (enable).
How storage is enabled
Data collection may be started through key actions from the operator interface keyboard or from digital
status signals from the controller. An “S” in the status line of the operator interface display indicates active
storage. [For detailed information concerning Data Storage Enable, refer to Overview of Data Storage
Enable Conditions (page 187).]