Triggering of Automatic Snapshots from DMC Calculations
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Products:
Aspen DMC3, Aspen DMC3 Builder
Last Updated:
05-Jan-2022
Last Updated:
05-Jan-2022
Versions:
Article ID:
000099415
Article ID:
000099415
Primary Subject:
Problem Statement
From Configure Online Server the automatic triggering of Snapshot from the controllers can be configured. However, this has a limitation of 1 hour (by default cannot be less than this period). This KB described an alternative way to Trigger the snapshots within a Default interval or Condition.
Solution
The workaround for this problem basically is to create an Input or output calculation that detects the condition to create the snapshot. this can be done on either DMCplus or DMC3. For purpose of the demonstration, this article will show the solution on a DMC3 controller.
The DMC3 controller can manually trigger a snapshot using the switch entry TriggerSnapshot which can be accessed on the General Section of the controller in PCWS (Click on the controller’s name in the Operations section). The goal of the calculation then is to create a condition that changes this switch from NO to YES.
This is a description of the Entry extracted from DMC3 Help file:
If the TriggerSnapshot entry value is Yes (1) at the end of a controller cycle, then the controller will create a new snapshot of the online application. The entry value can be changed on demand from PCWS, a User Calculation, or an IO Tag.
The RTE scheduler performs snapshots at the end of the application cycle based on certain conditions such as whether a snapshot was requested from DMC3 Builder, or an automatic snapshot is scheduled, or the controller is stopping. For v10 and later, the RTE Scheduler will also examine the value of TriggerSnapshot to decide whether to create an application snapshot. If a snapshot is produced, then the TriggerSnapshot entry will be reset to No. If TriggerSnapshot is changed from Yes to No, this will also output an operator message stating that a snapshot was triggered.
The following Calculation is an example of the use of the entry based on the condition of triggering a new snapshot on a five-minute interval. Every five minutes a new Snapshot will be created.
IMPORTANT NOTE:
The script shown is limited to be an example as the script may contain some failures that need to be fixed and may not adapt to all systems. The purpose of the example is just to show the use of the TriggerSnapshot entry.
mmnt = minute(lastrun)
’THIS SECTION IDENTIFIES THE NUMERICAL VALUE OF THE MINUTES FIELD OF THE TIMESTAMP
if
mmnt = 0
or
mmnt = 5
or
mmnt = 10
or
mmnt = 15
or
mmnt = 20
or
mmnt = 25
or
mmnt = 30
or
mmnt = 35
or
mmnt = 40
or
mmnt = 45
or
mmnt = 50
or
mmnt = 55
then
’THE CONDITION IS BASED ON TRRIGGERNIG SNAPSHOT ON A 5 MIN BASIS
trigger = 1
else
trigger = 0
end
if
In this example, the controller was running from 1:55 PM to 2:00 PM on a minute cycle period.
Keywords
DMC3, Snapshot, Calculations