Tutorials > Basic tutorials

DEWESoft offers many ways of how to store data. All settings for this are done in the Acquisition setup screen.

First, let's take a look at how we can name the files to be stored. We can define the file name for each measurement separately by entering it into the file name edit-field. The default folder where data is stored can be changed by clicking on the File details button.

File details

For repetitive measurements, it can be helpful to use the multifile function. Multifile automatically assigns a new file name for each cycle (start) of storage. File names can be either consecutive (such as 0001, 0002, 0003) or by the date and time.

Additionally, we can create a new file after a certain file size is reached or after a predefined time. This is done by selecting Make new file after check box. The criteria for switching to a new files are either the file size or time interval, which can be defined in seconds, minutes or hours.
In this case we may wish to switch the file after reaching absolute time. This can be very useful when acquiring data for longer time periods. If we choose to switch the file each hour with absolute time, then the switching will be done exactly on the hour (01:00, 02:00, 03:00...). The time will be taken from absolute PC time (or other more exact timing source, if available, as defined in the hardware setup). The file switching is done in such a way that no data point is lost in the process.

Storage options

We have four different storage options which relate to the basic sample rates:

-	always fast: data will be always stored at high speed, as defined by the dynamic acquisition rate

-	always slow: data will be always stored at reduced speed, as defined by the static/reduced rate

-	fast on trigger: data will be stored with the dynamic rate, once the trigger point occurs

-	fast on trigger, slow otherwise: data will be stored with the dynamic rate at trigger points, and with the reduced rate when there is no trigger.

Now let's look at each individual storage options. Before looking into that, it is worth explaining there are two types of channels in DEWESoft: synchronous and asynchronous channels.
Synchronous channels (like analog, counter or digital) are channels which are acquired at an exact predefined speed, defined by the dynamic acquisition rate. Asynchronous channels are channels where the rate is not known beforehand (PAD, CAN, GPS...). These channels are always acquired at the speed with which they come from the device. The picture below is a typical example of a red analog channel with a fixed rate and, a purple GPS channel. The user can see that the rate of the channel is not fixed.

Only the synchronous channels are influenced by the dynamic acquisition rate, so raising the sample rate will increase the amount of data stored. The asynchronous channels are not influenced by the sample rate, we need only ensure that the dynamic rate is faster than the rate of data coming from the asynchronous device.

For example, for CAN bus it is usually enough to acquire the data with 100 Hz; other sources like PAD or GPS are even slower. If there are only asynchronous channels, the sample rate only defines the time stamp precision (resolution).