Apis Logger
This module stores item data into the Apis Honeystore real-time trend historian. Data are retrieved through the Apis OPC HDA server and the APIS Hive UA server. Any OPC HDA and UA client can then access the data.
Global attributes
The Apis Logger registers 2 global attributes to the Hive:
- The regular global boolean attribute that turns trending on/off for the item in question, given the same name as the Apis Logger module itself, ie. LoggerName
- A global expression attribute that when used, represents an expression to be applied upon the value before it is stored to the database. The attribute is given the name LoggerName_Expr.
Logging of raw values (VQTs)
To store the raw VQTs of an item into a timeseries, you simply add the regular logger attribute (named LoggerName) to that item, and set its value to true.
Logging of calculated values (VQTs)
To store a derived, calculated value instead of the raw value, you also add the global expression attribute (name LoggerName_Expr) to the item, and specify the desired expression. You will also have to add and set the regular logger attribute to the item, and set its value to true.
When storing a calculated value, instead of the raw value, i.e. using the LoggerName_Expr attribute, the value type of the samples will typically be 8 byte float (unless the "calculation" result is a raw value), and the HDA quality part will be Calculated. Further, the name of the item in the HoneyStore database, will be the same as in the case of plain logging; the item ID in the Hive configuration.
Valid Expressions are the same as for the Calculations Operator of Legacy function item. There is one limitation however, you cannot use more than a single external input to the expression. Meaning just a single ex1 is allowed in the Expression.
Hint: If you would like to trend both the raw, as well as a calculated value of an item, you will need to use 2 different Apis Logger modules, targetting to different HoneyStore databases.
Also, then you should specify the TimeseriesAccessOrder of the logger modules.
Further, if you want to access timeseries for both stored items inside your Hive configuration,
you can use an ApisHSMirrorBee to expose the items having the higher TimeseriesAccessOrder.
Provider: Prediktor