User`s guide

Data Storage Configuration
Overview of Data Storage Enable Conditions
188 UMC800 Control Builder User’s Guide Release E
1/01
Three levels of enabling
Introduction
There are three levels of Data Storage Enable:
Data Storage Disable Signal (Operator Interface) – See Note 1.
Data Type Enable Signals
Batch Command Enable Signal
Note 1. Since any storage schedules loaded into the system automatically enables storage, the operator
interface can disable storage.
Data type enable signals
This level of control is the Data Type Enable Signal. Each data type (trends, point log, and alarms/events)
has its own Enable Signal that can either be configured as a digital signal on the LCB, or if not configured
as a digital signal (NONE selected on LCB Data Storage Configuration), it will appear on the Storage
Control menu on the operator interface
For example, if the Trend Enable Signal is configured as a digital signal in the LCB Data Storage
Configuration, it will not appear on the Storage Control menu on the operator interface. This is done to
avoid having two conflicting sources for the enable signal.
When a digital signal is not used, the Trend enable signal is set to enable when the configuration is loaded.
The Trends can then be disabled from the Operator Interface.
The Enable Signal has two functions for Point Log storage.
In Continuous and Batch modes, it enables Point Log storage to begin at the Start Time and at
every storage interval thereafter.
In On Command mode, when it changes from off (disable) to on (enable), it causes a single
sample of Point Log data to be stored at that moment (Figure 53).
Batch command enable signal
This level of control is the Batch Command. It is a single control signal that starts and stops storage for all
data types configured for batch storage.
It does not affect Continuous or On Command storage.
If the Batch Signal is configured as a digital signal in the LCB Data Storage Configuration, it will not
appear on the Storage Control menu on the Operator Interface. This is done to avoid having two
conflicting sources for the signal.
When a digital signal is not used and Batch storage has been selected, the Batch command signal is set to
Stop. Batches can be started from the Operator Interface.