Logger Tags
The logger tag type monitors the value of another tag and records that tag's data in RAM as well to a disk file. When a logger tag has been configured to record data for another tag, a data file and a log file are automatically generated by VTS. By default, the data file and log file are saved in the application's folder; however, you have the ability to specify a different path to which you wish these files to be saved. Information on doing so can be found in "VTS Programmer's Guide: Config.ini [SYSTEM] Section Settings Applicable to Data Logging". The data file is the name of the tag whose data is being recorded with the extension .DAT, while the log file is the name of the tag whose data is being recorded with the extension .LOG.
A logger tag can record data for any of the basic I/O tags, standard driver tags, or for any tag that has a numeric value (see Numeric Group for a list of standard tags with numeric values). A maximum of 100 properties can be recorded for the selected tag.
Note: Several tags have built-in loggers. A logger tag attached to any of these is unnecessary and, often, will not work. Never attach a logger tag to any of Pump Status tags, Digital Status tags, Analog Status tags, Counter tags or Totalizer tags.
It is recommended that only one logger be directly configured to record values per standard tag, due to the manner in which VTS configures the corresponding data file to which it saves the logged data. Currently, a tag's name is used to generate the data file to which a logger tag records, resulting in a data file whose naming convention is TagName.DAT. If multiple loggers are used to save data for the same tag, the result is that both loggers might attempt to log data to the same data file simultaneously; a process that could possibly result in errors. There is, however, a means by which you can still record data for a single tag.
If you wish to log the data from a single tag (e.g. an analog input tag) using multiple log rates, (i.e. once per second and once per hour), then it is recommended that you configure multiple calculation tags to accept the data from the analog input tag whose data you wish to record, then configure logger tags to record the data for each of the calculation tags. In doing so, the calculation tags mirror the analog input tag's data, and the logger tag can record one data file for each of the calculation tags. The logger tags recording data for each of the calculation tags that are mirroring the analog input tag's data can be configured with independent log rates. Detailed instructions on the configuration of calculation tags to facilitate data logging for a single tag are provided in Using Function Tags to Create Multiple Data Logs of an I/O Tag.
The value of a logger tag is the record number of the last record written to the data file. Other tags can use the value of a logger tag. For example, an alarm tag can be configured to monitor the value of the logger tag and trigger an alarm the data logging file is almost full.
Further information on the data logging files can be found in Log Manager Data Files.
Logger Tag Type Characteristics
Tag Browser Name: Logger
Database Table Name: LogPoint
Type: Attribute
Tag Group Memberships: None
Log Enabled Variables: None
Native Drawing Methods: No drawing methods available for the logger tag type
Logger Tag Type Properties: ID Tab