Format of the event history
- Last UpdatedOct 29, 2026
- 4 minute read
This topic describes the location and format of the event history that is saved during project run time, if the event logger is enabled.
By default, a project's alarm and event history is saved in Proprietary format. You can configure your project settings to save the alarm and event history in Database format. For more information, see Saving your alarm history / event log to an external database.
When your project is configured to save the history in Proprietary format (that is, when History Format is Proprietary), the event history is saved as sequentially numbered .evt files in your project folder. A new .evt file is created for each calendar day, and that file is named according to the following syntax:
EVYYMMDD.EVT
For example, the event history for 17 August 2018 is saved in your project folder at: <project name>\Alarm\EV180817.EVT
All of the event history for a given day is saved in the same file, regardless of whether the project is stopped and then restarted during that day. (In other words, restarting the project does not create an additional file for that day.) Each event is appended to the file as a new line, and each line comprises tab-separated values that describe the event. You can open the file with a text editor or spreadsheet program.
Tip: To change the location where your project saves its alarm and event history files, use the SetAppAlarmPath function.
When your project is configured to save the history in Database format (that is, when History Format is Database), the event history is saved in a table in the external database. All of the event history for the entire project is saved in a single table named EVENTHISTORY by default, although you can change that name in your project settings. Each event is inserted into the table as a new row.
The fields/columns of the event history are described below:
|
Proprietary |
Database |
Description |
|
|---|---|---|---|
|
Field Number |
Column Name |
Data Type |
|
|
P1 |
— |
Integer (int) |
Internal version number of the event history format. This information is saved only when History Format is Proprietary. You can use this information to differentiate between .evt files that were created by previous and current versions of this software. |
|
P2 |
Ev_Type |
Integer (int) |
Type of event:
|
|
P3 |
Ev_Time |
Timestamp (datetime) |
Timestamp that indicates when the event occurred. When History Format is Proprietary, the event time is saved in the local time zone (that is, in the time zone that is selected in the computer's settings) and in the following format: MM/DD/YYYY HH:MM:SS.mmm When History Format is Database, the event time is saved in Coordinated Universal Time (UTC) by default and in the database's native datetime format. If the database does not support milliseconds in its datetime format, the milliseconds portion is saved in Ev_Time_ms. |
|
— |
Ev_Time_ms |
Integer (int) |
The milliseconds portion of Ev_Time. This information is saved only when History Format is Database and the database does not support milliseconds in its datetime format. |
|
P4 |
Ev_Info |
String (varchar) |
Name of the project tag that is associated with the event. |
|
P5 |
Ev_Value |
Real (varchar) |
Value of the project tag when the event occurred. |
|
P6 |
Ev_Source |
String (varchar) |
Reserved. |
|
P7 |
Ev_User |
String (varchar) |
User who was logged on to the station when and where the event occurred. |
|
P8 |
Ev_User_Full |
String (varchar) |
Full name of the user who was logged on to the station when and where the event occurred. |
|
P9 |
Ev_Message |
String (varchar) |
Event message. |
|
P10 |
Ev_Station |
String (varchar) |
Name of the station where the event occurred. |
|
P11 |
Ev_Comment |
String (varchar) |
Comment entered by the user when the event occurred. User comments are optional. |
|
P12 |
Ev_Prev_Value |
Real (varchar) |
Value of the project tag before the event occurred. |
|
— |
Ev_Deleted |
Boolean (int) |
A numeric flag that indicates whether the user deleted the event message:
|
|
P13 |
Bias |
Integer (int) |
Difference (in minutes) between the local time zone and UTC, when the event is logged and the event time is saved. When History Format is Proprietary, this information is always saved because the event time is always saved in the local time zone. When History Format is Database, this information is saved only if the Local Time + Time Difference option (in your project settings) is also selected. |
|
P14 … P23 |
Ev_Custom1 … Ev_Custom10 |
String (varchar) |
Up to 10 user-defined custom fields. |
|
— |
Last_Update |
Timestamp (datetime) |
Timestamp that indicates when the database entry was created or last updated. This information is saved only when History Format is Database. The update time is saved in Coordinated Universal Time (UTC) and in the database's native datetime format. If the database does not support milliseconds in its datetime format, the milliseconds portion is saved in Last_Update_ms. This information is used to synchronize databases when the project is configured to use the Secondary Database in addition to the Primary Database. |
|
— |
Last_Update_ms |
Integer (int) |
The milliseconds portion of Last_Update. This information is saved only when History Format is Database and the database does not support milliseconds in its datetime format. |
Tip: To customize the column names in the database table, manually edit your project file
(<project name>.APP) as follows:
[EventLogger]
<default column name>=<custom column name>
For example:
[EventLogger]
Ev_Info=TagName
Ev_Message=Message