Data Log Models editor - Log Triggers tab

The following table shows options in the tab if you select
Periodic
.
Option
Description
Periodic
Select this option to log tag values periodically.
Interval
Type a number and select a time unit to specify how often tag values are logged. All tags are logged each time this interval expires.
  • The Data Log supports a 10ms minimum scan rate. The maximum guaranteed precision that the Data Logger can provide is at 20ms for the data.
  • Pick practical scan rates for your application no matter you choose DataStorePlus ActiveX Control or Data Log Model. As the network speed and bandwidth will determine how fast you are able to update your tags.
  • If you need to capture data which is changing in the PLC at one second interval, you need to set the scan rate at 500ms. This way you can guarantee its one second data capture precision. In this example, you can only choose the built-in Data Log.
  • If you need to capture data which is changing in the PLC at a five second interval, you need to set the scan rate at about 2.5 seconds. This will guarantee the data being captured with a precision of five seconds. In this example, you could choose either.
The following table shows options in the tab if you select
On Change
.
Option
Description
On Change
Select this option to only log tags whose values have changed.
Use the
On Change
 trigger to log tag values after a certain percentage of change in the value occurs. The percentage is based on the tag's minimum and maximum (or High EU and Low EU) values. For example, if you specify 10, a tag's value must change by 10 percent before it is logged. This applies to analog HMI tags only. For data server tags, and digital and string HMI tags, which do not have minimum and maximum properties, every change is logged.
Maximum Update Rate
Click an item in the
seconds
 list to select the maximum rate at which tags in the data log model are updated. The default maximum rate at which tags are updated is 1 second.
Change Percentage
Type the percent a tag value must change to trigger logging. Zero means all changes are logged. The change percentage can contain decimals.
Heartbeat
Type a time and click a time unit to specify how often tag values are logged even if no change has occurred. The heartbeat ensures that the data in the log file is current. The heartbeat rate must be equal to, or greater than, the update rate.
Specify 0 for the heartbeat if you do not want to use it. Tag values will be logged only when they change.
The following table shows options in the tab if you select
On Demand
.
Option
Description
On Demand
Select this option to log tag values when the FactoryTalk View command
DataLogSnapshot
 is issued.
This command can issued anywhere that other FactoryTalk View commands and macros can be. For example, you can type it in the command line, or specify it as the action for an event. If you specify
Periodic
 or
On Change
, you can still use
On Demand
 logging whenever it is appropriate.
Maximum Update Rate
Click an item in the
seconds
 list to select the maximum rate at which tags in the data log model are updated. The default maximum rate at which tags are updated is 1 second.
Provide Feedback
Have questions or feedback about this documentation? Please submit your feedback here.
Normal