Data loggers are very useful tools when temperature, humidity, pressure, current, voltage, shock or other measured variables need to be monitored over a certain period of time. However, the decisive factor is not only the measuring device itself, but also the correct configuration. An incorrectly configured data logger can miss important events, store unnecessarily large amounts of measured values or discharge the battery much faster than necessary.
Measuring intervals are selected incorrectly particularly often. If measurements are taken too rarely, short temperature peaks, humidity fluctuations, pressure drops or current peaks remain undetected. If measurements are taken too frequently, the memory fills up unnecessarily quickly and battery life decreases. Start delay, alarm limits, memory type and measuring duration must also match the application.
This article explains how data loggers are configured correctly, how measuring interval, memory size, battery life and limit values are connected, and what must be considered especially in long-term monitoring, troubleshooting and documentation.
Table of contents
- Why the correct data logger setting is so important
- Measuring interval: How often should measured values be recorded?
- Long-term monitoring or rapid troubleshooting?
- Correctly estimating memory size
- Taking battery life into account
- Using start delay and start condition sensibly
- Setting alarm limits and limit values correctly
- Measuring interval for temperature monitoring
- Measuring interval for humidity and dew point
- Measuring interval for pressure measurements
- Measuring interval for current and voltage
- Measuring interval for shock, vibration and transport
- Table: Application, measuring interval and notes
- Practical example: Warehouse monitoring over 30 days
- Typical errors in data logger configuration
- Conclusion: Always consider measuring interval, memory and battery together
- FAQ: Frequently asked questions about configuring data loggers
Why the correct data logger setting is so important
A data logger is intended to reliably record and document measured values. For this to work, measuring interval, measuring duration, memory size, battery capacity and alarm limits must match the application. A standard configuration is often not optimal.
A measuring interval that is too long can result in short events not being detected. This is critical, for example, with temperature peaks in cold rooms, humidity peaks in warehouses, pressure drops in systems or current peaks on machines. If the logger measures only every 30 minutes, an event lasting only a few minutes can occur completely between two measuring points.
A measuring interval that is too short, on the other hand, generates very large amounts of data. This can be useful when fast changes need to be analysed. For simple long-term monitoring, however, it is often unnecessary. Memory and battery are loaded more heavily, and the evaluation becomes less clear.
The correct setting therefore always depends on the question: What should be detected? A long-term trend, a limit value violation, a short outlier or a sporadic fault?
Measuring interval: How often should measured values be recorded?
The measuring interval determines how often the data logger stores a measured value. An interval of 1 minute means that 60 measured values are created per hour. An interval of 15 minutes produces only 4 measured values per hour. This difference directly affects memory requirements, battery life and the level of detail in the recording.
For slow processes, a longer measuring interval is often sufficient. For room temperature, warehouse monitoring or long-term humidity observation, 5, 10, 15 or 30 minutes may be sufficient. For fast processes, troubleshooting or short-term events, significantly shorter intervals are required.
The rule of thumb is: The measuring interval must be significantly shorter than the event that is to be detected. If a temperature peak of 5 minutes is to be reliably detected, measurement should not be carried out only every 15 minutes. In this case, an interval of 30 seconds or 1 minute, for example, would be more appropriate.
At the same time, measurements should not be taken unnecessarily quickly. In many cases, a warehouse room whose temperature changes only slowly does not need to be recorded every second.
Long-term monitoring or rapid troubleshooting?
When configuring a data logger, it must first be clarified whether long-term monitoring or troubleshooting is being carried out. Both tasks have different requirements.
Long-term monitoring is usually about documenting trends, limit value violations and regular patterns. Examples include warehouses, cold rooms, archives, production rooms, transport monitoring or indoor climate. Here, measuring intervals of several minutes are often sufficient.
Troubleshooting, on the other hand, is about making short or sporadic events visible. Examples include short voltage dips, pressure drops, current peaks, temperature peaks when doors are opened or humidity peaks after cleaning processes. Here, the measuring interval must be selected significantly shorter.
A sensible strategy can be to start with a shorter interval for troubleshooting and later switch to a longer interval for permanent monitoring. This allows the cause of the fault to be detected without generating unnecessarily large amounts of data during continuous operation.
Correctly estimating memory size
The memory size of a data logger determines how many measured values can be recorded. The decisive factor is not only the absolute number of memory locations, but also the number of channels and the selected measuring interval.
A logger with one channel and 10,000 memory values can record around 10,000 minutes at a measuring interval of 1 minute. This corresponds to around 166 hours or just under 7 days. With an interval of 10 minutes, the same memory is sufficient for around 69 days.
With multiple channels, it must be taken into account whether memory locations are used per channel. A temperature and humidity logger often stores two measured values at each point in time. This can reduce the possible recording duration compared with a single-channel logger.
Before starting a measurement, it should therefore be roughly calculated whether the memory is sufficient for the planned measuring duration. This is especially important for transport monitoring, long-term measurements or measurements at locations that are difficult to access.
Taking battery life into account
Battery life depends heavily on the logger design, measuring interval, ambient temperature, sensor technology, display use and data transmission. Frequent measurements, wireless transmission, alarm functions or very low temperatures can shorten the operating time.
A data logger that measures every second generally requires more energy than a logger that measures every 10 minutes. Frequent readout, active display or wireless communication can also require additional energy.
Battery life should be checked in advance, especially for refrigerated transport, outdoor applications or long-term measurements. Low temperatures can additionally stress batteries and reduce the available capacity.
A safety margin should be planned for critical measurements. If a measurement is to last 30 days, the battery should not only theoretically last 31 days. A clear reserve is better so that the recording does not stop shortly before the end.
Using start delay and start condition sensibly
Many data loggers offer different start options. Recording can begin immediately, start at a defined time, begin after a delay or be triggered by a button or an event.
A start delay is particularly useful if the logger should only start recording after it has been placed at the measuring location. This prevents transport, handling or setup phases from being recorded unnecessarily.
For transport measurements, starting by button can be practical. The logger is prepared and activated only when loading begins. For warehouse monitoring, a planned start time can be useful, for example Monday morning at the start of a test period.
It is important to document the start condition clearly. Otherwise, it may later be unclear whether measured values come from the setup phase, transport or the actual monitoring period.
Setting alarm limits and limit values correctly
Alarm limits help to detect critical conditions quickly. However, they should not be set arbitrarily, but must match the application, product, process and permissible tolerance.
For temperature monitoring, upper and lower limit values may be important. For humidity monitoring, maximum values or dew point limits are often relevant. For pressure, current or voltage, limit values can indicate overload, leakage, failure or unstable supply.
Alarm limits that are too narrow lead to frequent false alarms. Alarm limits that are too wide may detect critical conditions too late. In addition, an alarm delay can be useful so that brief uncritical fluctuations are not immediately evaluated as faults.
Example: A cold room may temporarily become somewhat warmer when the door is opened. The decisive factor is whether the temperature rises only briefly or remains outside the permissible range for a longer period. Here, a combination of limit value and time criterion can be useful.
Measuring interval for temperature monitoring
Temperature measurements are one of the most common applications for data loggers. The appropriate measuring interval depends strongly on how quickly the temperature can change and which events need to be detected.
For warehouses, archives or indoor climate, an interval of 5 to 30 minutes is often sufficient. For cold rooms, a shorter interval can be useful if door openings, defrost cycles or short temperature peaks need to be evaluated.
For machines, test benches or processes with fast temperature changes, shorter intervals are required. Here, intervals in seconds may be useful if heating or cooling processes need to be evaluated in detail.
The response time of the sensor is also important. A very short measuring interval is of little use if the sensor itself reacts slowly or is strongly delayed by the housing, installation position or medium.
Measuring interval for humidity and dew point
Humidity and dew point measurements often react more slowly than electrical measured variables. Nevertheless, humidity peaks can be important, for example during condensation, cleaning, ventilation, storage or compressed air monitoring.
For indoor climate and warehouse monitoring, intervals of 5 to 15 minutes are often useful. For slow long-term trends, 30 minutes may also be sufficient. For troubleshooting, condensation problems or fast process changes, shorter intervals should be used.
Humidity sensors often require a certain adjustment time. Therefore, the measuring location should be selected carefully. A poor position can be more important than the measuring interval. Measurements directly next to doors, ventilation outlets or heat sources can fluctuate strongly.
For compressed air or dew point monitoring, trend recording over several operating states can be very helpful. This makes it possible to see whether problems occur only during load peaks, standstill or certain switching states.
Measuring interval for pressure measurements
For pressure measurements, the correct interval depends heavily on the application. A slowly falling pressure in a closed system can be monitored with intervals of several seconds or minutes. Fast pressure surges, pump pulsations or leakage events require significantly shorter measuring intervals.
For leakage tests, a uniform interval is often useful to document the pressure curve over a defined period. For fast pressure peaks, a normal data logger may not be sufficient if the sampling rate and memory function are not fast enough.
Pressure measurements must also distinguish between trend monitoring and event detection. A pressure drop overnight can be detected with a longer interval. A short pressure surge during valve switching requires fast measurement.
For very dynamic pressure events, it should be checked whether the data logger, sensor and measuring setup are suitable for the required speed.
Measuring interval for current and voltage
Current and voltage measurements can have very different requirements. For energy consumption, load profiles or long-term monitoring, longer intervals of several seconds to minutes are often sufficient. For voltage dips, inrush currents or short load peaks, significantly faster measurements are required.
A data logger with an interval that is too long can completely miss short electrical events. For example, if a machine draws a high current for only a few seconds, this may not be detected with a measuring interval of 1 minute.
For electrical measurements, it is also important whether RMS values, instantaneous values, min/max values or events are stored. Some loggers can capture minimum and maximum values between two stored points. This can be very helpful for fluctuating signals.
For measurements on frequency inverters, switched-mode power supplies or non-sinusoidal signals, it must also be checked whether the measuring instrument is suitable for the signal waveform.
Measuring interval for shock, vibration and transport
Shock and vibration measurements have different requirements than slow temperature or humidity measurements. Shock events are often very short. A measuring interval that is too slow can miss such events completely.
Many shock loggers therefore do not work only with fixed time intervals, but with event thresholds. For example, the device stores data when a defined acceleration is exceeded. This saves memory and specifically documents relevant events.
For transport monitoring, it is important to set limit values, start time, measuring duration and memory type correctly. If the logger is set too sensitively, many irrelevant events are generated. If it is set too insensitively, critical impacts are not detected.
Mounting is also decisive. A shock logger must be attached in such a way that it records the load on the package, device or component in a truly representative manner.
Table: Application, measuring interval and notes
| Application | Typical measuring interval | Important note |
|---|---|---|
| Warehouse temperature monitoring | 5 to 30 minutes | Usually sufficient for long-term trends |
| Cold room monitoring | 1 to 10 minutes | Consider door openings and defrost cycles |
| Transport temperature monitoring | 1 to 15 minutes | Observe measuring duration and battery life |
| Indoor climate / humidity | 5 to 15 minutes | Select measuring location carefully |
| Compressed air dew point | 1 to 10 minutes | Record load changes and dryer behaviour |
| Pressure leakage test | 1 second to 1 minute | Depends on the expected pressure change |
| Current and load profile | 1 second to 15 minutes | Min/max values can be helpful |
| Voltage dip / current peak | Very short or event recording | Normal long-term loggers may be too slow |
| Shock / transport impact | Event-dependent | Limit value and mounting position are decisive |
Practical example: Warehouse monitoring over 30 days
A warehouse is to be monitored over 30 days. The temperature must not exceed certain limit values, and it must be documented whether the storage conditions were maintained throughout the entire period. The data logger has sufficient memory, but the battery should be conserved.
First, it is clarified how quickly relevant temperature changes can occur in the warehouse. Since it is a relatively slow-reacting room, a measuring interval of 10 minutes is sufficient. This results in 144 measured values per day. Over 30 days, this gives 4,320 measured values per channel.
If humidity is also recorded, two channels generate around 8,640 measured values. The logger memory must therefore be able to store at least this number plus a safety reserve. At the same time, a 10-minute interval is much more battery-friendly than measuring every second.
Upper and lower limit values are defined for alarming. It is also checked whether brief door openings may trigger an alarm or whether an alarm delay is useful. The logger is programmed with start time, measuring interval, limit values and sufficient battery reserve.
The example shows: The suitable setting results from measuring duration, process speed, memory size, number of channels, battery life and permissible limit values. Only when these points are considered together will the recording be meaningful later.
Typical errors in data logger configuration
A common error is a measuring interval that is too long. As a result, short events are not detected. Especially during troubleshooting, door openings, pressure drops, current peaks or shock events, this can cause the actual fault to remain invisible.
Another error is an unnecessarily short measuring interval. The memory fills up quickly, the battery is loaded more heavily and the evaluation becomes confusing. For slow long-term monitoring, measuring every second is usually not necessary.
Incorrectly set alarm limits also lead to problems. Limits that are too narrow generate false alarms, while limits that are too wide detect critical conditions too late. Alarm limits should always match the application and the permissible tolerance.
It is also often forgotten to check memory capacity and battery life before starting the measurement. This can cause a measurement to end prematurely or important data to be overwritten.
Conclusion: Always consider measuring interval, memory and battery together
A data logger only provides meaningful data if it is configured correctly. The measuring interval must match the speed of the process. The memory size must be sufficient for measuring duration and number of channels. Battery life must be planned with adequate reserve. Limit values and start conditions must match the application.
For long-term monitoring, longer intervals are usually useful. For troubleshooting and short events, significantly shorter intervals or event functions must be selected. The decisive factor is always which change is to be detected and how quickly this change can occur.
If measuring interval, memory, battery and limit values are properly defined in advance, data gaps, unnecessary data volumes and unusable measurement series can be avoided. This turns the data logger into a reliable tool for documentation, quality assurance and troubleshooting.
FAQ: Frequently asked questions about configuring data loggers
How do I set the correct measuring interval?
The measuring interval should match the speed of the process. The faster the measured value can change, the shorter the interval must be. For slow long-term monitoring, several minutes are often sufficient.
What happens if the measuring interval is too long?
Short events such as temperature peaks, pressure drops, current peaks or door openings can be missed if they occur between two measuring points.
What happens if the measuring interval is too short?
The memory fills up faster, the battery is loaded more heavily and the evaluation can become unnecessarily extensive.
How do you calculate the memory range of a data logger?
Divide the number of available memory values by the number of stored values per time unit. With several channels, it must be taken into account that multiple values may be stored at each measuring point.
How does the measuring interval affect battery life?
Short measuring intervals usually require more energy because measurement and storage occur more frequently. Display, wireless transmission and low temperatures can additionally shorten battery life.
Which measuring intervals are useful for temperature data loggers?
For warehouses or indoor climate, 5 to 30 minutes are often useful. For cold rooms, troubleshooting or fast temperature changes, 1 minute or shorter intervals may be required.
How often should humidity be recorded?
For indoor climate or warehouse monitoring, 5 to 15 minutes are often suitable. For condensation problems or rapid troubleshooting, a shorter interval can be useful.
What is a start delay?
A start delay means that the logger only begins recording after a defined time. This is useful when transport or setup should not be recorded.
How do you set useful alarm limits?
Alarm limits should be based on permissible process, product or quality limits. For brief uncritical fluctuations, an additional alarm delay can be useful.
Why are min/max values helpful?
Min/max values can make short peaks visible, even if the normal storage interval is relatively long. This is particularly helpful for fluctuating measured variables.
Which data logger is suitable for troubleshooting?
For troubleshooting, the logger should offer sufficiently short measuring intervals, suitable sensors, enough memory and, if necessary, event or min/max functions.
What should be checked before starting a measurement?
Before starting, measuring interval, measuring duration, memory range, battery life, number of channels, limit values, start time and measuring location should be checked.