Task parameter

From the list, select the task in which data acquisition is executed. In general, the trend recording runs in the same task as the main program, for example, PLC_PRG.

Record condition parameter

Refers to a variable of the type BOOL, to a bit or to a property. The data acquisition is executed if the value is TRUE. The setting is optional.

Comment parameter

Enter a comment text.

Resolution parameter

Resolution with which the time stamp is acquired.

Set the resolution of the time stamp to 1 μs if the trend task has a cycle time of 1 ms or less.

Trend storage... button

Click this button to open the Trend storage dialog box. It allows you to configure further parameters that concern the behavior of the trend recording at runtime.

Advanced... button

Click this button to open the Advanced Trend Settings dialog box. It allows you to configure parameters that concern the acquisition and storage of data.

Maximum number of variables

Defines the maximum number of trend variables that are managed in the database. If you modify this value, EcoStruxure Machine Expert updates the database on the controller by forcing a download during next login to the controller. The database will then be uploaded from the controller, the variables of the database will be increased or decreased according to this new setting, and will be downloaded to the controller.

Store every N milliseconds

Number of ms defining the time interval at which the recorded data is temporarily stored in a local buffer before being stored persistently in the database. The time interval is converted internally to the number of task cycles. The duration of a task cycle is defined in the task configuration.

A high value results in a better runtime performance. The disadvantage of this is that the greater the value, the amount of data subject to be lost in the case of a controller change of state is likewise increased.

A low value reduces this risk. The disadvantage of this is that the control of a trend visualization is degraded with large amounts of data.

Limit

Activate an option to limit the recording.

No Limit

The amount of trend recording data that is stored is not limited.

Use this option only for testing purposes, as using this setting will eventually exhaust the file space in the controller if not regularly maintained.

Maximum number of records

This option defines the maximum number of data records that are stored in the database. Each data record consists of time stamp and the values of the trend variables.

NOTE: If this limit is reached, trend recording is stopped.

Maximum storage size

This option defines the maximum memory size reserved for trend storage. The number of records that can be stored within this memory depends on the size of the individual records.

Select the suitable unit from the list (kilobytes (Kb), megabytes (Mb), or gigabytes (GB)).

NOTE: If the memory reserved for trend storage is full, trend recording continues, overwriting the oldest records.

Measure in every n-th cycle

Defines how often data is acquired by the runtime system, depending on the number of cycles completed.

The time interval is calculated according to the frequency by using the settings from the task configuration. Thus, the calculation can only be performed if at least the task cycle time is set. The result is shown on the right of the input field, for example, 1h1m1s1ms.

The default setting is 1. This means that data is acquired every cycle.

Additional Runtime Buffer for

Defines the time, in ms, that the runtime system can use an additional “overflow” buffer for recording data.

Example: 1000 ms

NOTE: This additional buffer can help to avoid loss of data if a delay occurs during storage of the trend data.