Micromod Micro-PWC: 53PW6000 MicroPWC Configuration Guide - Manual (Page 246)

Micro-PWC CONFIGURATION GUIDE
226 Historical Database
5.2.2.2 Computations
The Micro-PWC can be configured to perform calculations on historical data as it is collected. Available
calculations are:
• Average
• Minimum
• Maximum
• Standard deviation
Computations can be performed hourly, daily, monthly or yearly. The computed values are stored in Histor-
ical Computation atoms. The computed values stored in these atoms can be used by other applications,
such as trending. Atoms are also provided for two additional values, minimum time and maximum time.
These atoms are used to store the timestamp of the first instance of the minimum and maximum collection
values. The atom names are shown in
Table 5-1 .
Click the Computations button to display the Historical Tag Computations window ( Figure 5-7 ).
The Historical Tag Computations window is composed of a matrix of toggle buttons which allows selection
of combinations of computation rate and computation type. Each row in the matrix represents a computa-
tion rate; each column represents a computation type. By default, all buttons are deselected and displayed
in gray and appear raised. Click the toggle button which corresponds to the desired computation rate and
computation type.
Use the Number Retained text entry box at the end of each row to define the number of values to be
retained for each computation type selected for that computation rate. Once the retention limit has been
reached, the value obtained by each new computation will replace the oldest value. Because the retention
limit is defined on a per computation rate basis, it is not possible to set the Number Retained to a different
Table 5-1. Historical Computation Atoms
Period Average Minimum
Minimum
Time
Maximum
Maximum
Time
Standard
Deviation
Hourly .HAV .HMN .HTMN .HMX .HTMX .HSD
Daily .DAV .DMN .DTMN .DMX .DTMX .DSD
Monthly .MAV .MMN .MTMN .MMX .MTMX .MSD
Yearly .YAV .YMN .YTMN .YMX .YTMX .YSD
TC00202A
Figure 5-7. Historical Tag Computations Window