Micromod Micro-PWC: 53PW6000 MicroPWC Configuration Guide - Manual (Page 249)

Micro-PWC CONFIGURATION GUIDE
Historical Database 229
5.2.2.7 Event Bit
The information collected into the historical database is gathered based on one of the following:
• Collection rate (refer to Section 5.2.2.1, Collection Rate ).
• Event bit condition.
• Collection rate during the duration of an event bit condition.
Event bits are a set of 4,096 group wide event flags which can be set to indicate that an event has
occurred. Event bits are set and reset via blockware program commands. Names can be assigned to event
bits in the same manner as they are assigned to plant areas; this assignment is performed from the Net-
work Parameters menu discussed in
Section 2.6, Configuring Network Parameters .
The assignment of an event bit to a point in the historical database allows the collection of data when the
condition indicated by the event bit occurs. If the collection rate is set to None, then the data will be col-
lected only on transition of the event bit to the active value (refer to
Section 5.2.2.8, Active Value ). If a col-
lection rate other than None has been selected, data will be collected at that rate as long as the event bit is
set to the active value.
To assign an event bit to trigger data collection for the historical database point, click the Event Bit entry
box to gain focus on it, then enter the event bit number (one to 4,096) or the event bit name (as defined
using submenus of the Network Parameters menu).
5.2.2.8 Active Value
The active value is relevant only when the event bit is used. Use the active value to define the state of the
event bit (zero or one) which triggers the collection; the Active Value button displays the value which cur-
rently defines whether an event bit of one or zero will trigger collection of data for the historical database
point. Click the button to toggle between the two values.
5.2.2.9 Acknowledge Bit
The acknowledge bit is an event bit. It is used to confirm that a collection operation has been completed.
Click the Acknowledge Bit entry box and enter the name or number of the event bit to be used as the
acknowledge bit. When the event bit is set, it is toggled from its current state to the alternate state (i.e.,
from 1 to 0 or from 0 to 1).
A change to the state of the acknowledge bit can be used to trigger another collection.
5.2.3 Storage Information
The portion of the historical tag configuration display devoted to storage information provides the ability to
configure the length of time data will be retained, to determine the number of collections to be retained, and
to specify which Micro-PWC nodes will be used to store the data collected for the point.