Good point.
The "Old/Legacy/Data/IA Series" Historian (did any program every have so
many names?) uses the OM API. The OM API has the ability to set the update
scan rate on the list. The Historian uses this feature. However, the rate is
adjustable only between 0.5 seconds in 10s in 0.5 second increments.
A zero (0) delta will result in a change report each configured scan cycle.
However, if the scan rates for points on a list are not uniform, the fastest
scan rate wins. Determining which points are on which list can be determined
by noting that the Historian assigns them in groups of 50 to a list. Each
list runs at the rate of the fastest point on it.
PI and IP.21 use AIS calls.
When run on AIS (FoxAPI V3.0), these calls would also adjust the
update scan rate to between 0.5s and 10s in 0.5 second increments. A zero
(0) change delta results in a change each scan rate as set by the data set
opened by the application.
When run on FoxAPI V4.x, the scan rate specified by the application
is ignored. The scan rate will be the value of 'fastest_rsr' as set in the
file foxapi.cfg when FoxAPI is started. The default is 0.5 seconds. A zero
(0) change delta results in a change each scan rate as set by fastest_rsr.
FoxHistory V1.x through 2.0 uses only FoxAPI V4.x calls. All updates are as
set by 'fastest_rsr' as set in the file foxapi.cfg when FoxAPI is started.
FoxHistory V2.5 uses only FoxAPI V5.x calls. All updates are as set by
'fastest_rsr' as set in the file foxapi.cfg when FoxAPI is started.
AIM*Historian uses only AIM*API (renamed FoxAPI V5.x) calls. All updates are
as set by fastest_rsr in the aimapi.cfg file in /opt/aim/bin when AIM*API is
started.
Regards,
Alex Johnson
The Foxboro Company
10707 Haddington
Houston, TX 77043
713.722.2859 (v)
713.722.2700 (sb)
713.932.0222 (f)
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
-----Original Message-----
From: Cyrus W. Taft [SMTP:[EMAIL PROTECTED]]
Sent: Wednesday, August 30, 2000 10:18 AM
To: Foxboro DCS Mail List
Subject: RE: Event triggered data collection
Message text written by "Foxboro DCS Mail List"
>To generate a change in the historian, set the change delta to a
very,
very small number,
but not zero (0). A zero change delta will result in a new value in
the
historian every 0.5 seconds.<
Alex,
Will a 0.0 deadband make to historian record a new value every 0.5
seconds
or at the minimum sample time specified for the point in the
historian
configuration? As I recall you can set the minimum sample time to
be 2, 4,
10, 30, 60 seconds, etc.
Cyrus Taft
EPRI I&C Center
-----------------------------------------------------------------------
This list is neither sponsored nor endorsed by the Foxboro Company.
All postings from this list are the work of list subscribers and no warranty
is made or implied as to the accuracy of any information disseminated
through this medium. By subscribing to this list you agree to hold the list
sponsor(s) blameless for any and all mishaps which might occur due to your
application of information received from this mailing list.
To be removed from this list, send mail to
[EMAIL PROTECTED]
with "unsubscribe foxboro" in the Subject. Or, send any mail to
[EMAIL PROTECTED]
-----------------------------------------------------------------------
This list is neither sponsored nor endorsed by the Foxboro Company. All
postings from this list are the work of list subscribers and no warranty
is made or implied as to the accuracy of any information disseminated
through this medium. By subscribing to this list you agree to hold the
list sponsor(s) blameless for any and all mishaps which might occur due to
your application of information received from this mailing list.
To be removed from this list, send mail to
[EMAIL PROTECTED]
with "unsubscribe foxboro" in the Subject. Or, send any mail to
[EMAIL PROTECTED]
