Deadband filter plugin for Data Loggers

Latest version: 5.0.1 build 1126. November 28, 2025.

The Deadband filter plugin helps you reduce the volume of exported data without losing important information. It removes records where the measured values change only slightly or change too often with no real impact. This is useful when you monitor stable signals or slow processes and want to avoid huge log files or oversized databases. The plugin works with our data loggers, such as Data Logger Suite, and may use several methods to decide which records should be exported.

In many industrial and IT systems, sensors and devices send new values every second, or even more often. For example, a temperature tag may report values like 50.01, 50.02, 50.00, 50.01. All these records consume storage and network resources, but they do not change your analysis or reports. The Deadband plugin filters out such minor fluctuations and keeps only meaningful changes. You can control the filter behavior using four modes: absolute, percent, time limit, and count limit. You can use each mode alone or combine them with an AND or OR relationship to match your process requirements.

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The plugin integrates into the logger data flow after the data parser and before the export module. First, a parser extracts variables, such as temperature, pressure, current, or any numeric field, from raw data. Then the Deadband plugin receives these values and decides whether to pass or ignore each record. Only records that pass the filter go to export, for example, to CSV, Excel, a database, OPC, or another destination. If the parser returns an empty (null) value for a variable, the plugin ignores that variable automatically, so it will not affect your filter logic.

Example with Advanced Serial Data Logger

For example, a serial device that sends temperature and pressure values every second to Advanced Serial Data Logger. An incoming data line looks like this:

2025-11-28 08:00:00;T=50.01;P=1.98

The parser extracts three variables: DATE_TIME_STAMP, Temp, and Press. DATE_TIME_STAMP holds the timestamp, "Temp" is the temperature value, and "Press" is the pressure value. You configure the Deadband plugin to use:

Absolute deadband for "Temp" with a threshold of 0.5.
Percent deadband for "Press" with a threshold of 3%.
OR relationship between absolute and percent deadbands.

Now imagine the following incoming data sequence:

2025-11-28 08:00:00;T=50.01;P=1.98
2025-11-28 08:00:01;T=50.02;P=1.99
2025-11-28 08:00:02;T=50.10;P=2.01
2025-11-28 08:04:59;T=50.12;P=2.02
2025-11-28 08:05:01;T=50.15;P=2.10

The first record at 2025-11-28 08:00:00 is stored and sets the baseline: Temp = 50.01, Press = 1.98. The second record at 08:00:01 shows small changes, which are below the absolute and percent thresholds, so it is ignored. The third record at 08:00:02 may exceed the absolute deadband for Temp or the percent deadband for Press, so it is recorded and becomes the new baseline. The record at 08:04:59 brings only minor change and is ignored.

Practical usage tips

For most projects, it is a good idea to start with the deadband thresholds set to zero. This means that the plugin initially records all values, and you can observe the natural data rate in your system. Then you can gradually increase the absolute or percent thresholds and, if necessary, add a time limit or count limit. After each adjustment, check how many records are exported and confirm that all important events remain visible in charts or alarms.

Absolute deadband is suitable when you have clear physical units. For example, use it for temperature in degrees, pressure in bar, or speed in RPM when you know what minimum change matters. Percent deadband is often better when values have a wide range, such as flow rate or power, and you want to track relative variation. A time limit and count limit are recommended to avoid too long gaps in exported data. They ensure that you still receive occasional records even during steady operation, which is useful for audit trails, regulatory requirements, or system health checks.

Summary

The Deadband filter plugin improves storage efficiency, network usage, and processing time while keeping your data meaningful and readable. It filters minor or too frequent changes and works together with both serial and TCP/IP data sources.

Key features

Supports four deadband methods: absolute, percent, time limit, and count limit.
Works with up to 8 parsed variables per plugin instance.
Flexible AND/OR logic when combining several deadband types.
Seamless integration with most of our data loggers.
Reduces Excel and database size while preserving essential trends and events.
Simple configuration.