Micromod Micro-PWC: 53PW6000 MicroPWC Configuration Guide - Manual (Page 247)

Micro-PWC CONFIGURATION GUIDE
Historical Database 227
value for different computation types with the same computation rate. For example, it is not possible to set
a different Number Retained for the hourly/average and hourly/minimum values. However, it is possible to
configure different retention limits for hourly/average and daily/average values. Enter
inf (infinity) in the
Number Retained text entry box to retain all values collected; otherwise, enter a numeric value (zero is not
a valid numeric value). To retain no data for a particular computation type, all toggle buttons for the compu-
tation type must be deselected.
5.2.2.3 Storage Rate
Storage rate is used to define the number of collections which will occur before a value is actually stored in
the historical database; it is a multiple of the collection rate. For example, if a point has a collection rate of
one second and a storage rate of 10, then only data for every tenth collection would actually be stored in
the historical database.
The default storage rate is one; to change the storage rate, click the button which displays the value of the
storage rate. The Storage Rate window (
Figure 5-8 )will appear.
Valid storage rates are one, two, five, six, 10, 20, 30, 60 and 120. Select the desired storage rate by click-
ing on it. The selected item will be highlighted. Click OK to complete the operation.
5.2.2.4 Collection Option
The Collection Option parameter on the Historical Tag Configuration window is used to define the form in
which collected values are stored. Available options include AVeraGe, MINimum, MAXimum and INSTan-
taneous. The default collection option is AVG; to change this, click the button which displays the current
✎ Note No checks are performed to validate collection rate vs. computation
rate. The user must consider the collection rate of the data and take
care to configure appropriate computation rates; i.e., while it is
technically feasible to perform hourly computations on data which is
collected once a day (daily), such a configuration would result in
many unnecessary and non-productive computations.
TC00203A
Figure 5-8. Storage Rate Window