Buffer

The Main Preference Pane permits you to change the internal buffer length of data recording. This section describes what that is and how and why to do that.

By default, DAQ Plot will store the last 864,000 values per channel. At any point in time all data is retained until you reach 864,000 values per channel and then the last 864,000 are retained. For example, if you have sampled 1,000,000 values per channel then DAQ Plot will retain the last 864,000 values and the first 136,000 values are lost forever. You can adjust this parameter according to the following criterion:

Increase the buffer length: By increasing the buffer length you will be able to store more data. If you apply 10000000 instead of 864000 then you will be able to store 10 million data values per channel before you start to loose the earliest data values.
Infinite buffer length: If you set the buffer length to zero (0) then the data storage is unbounded. That is good if you are aware that at some point you will run out of memory resources.
Constrained buffer length: Sometimes you may be interested in only a certain amount of data, for example the last 10 minutes of data. If you sample at 100Hz then setting the buffer length to 6000 will accomplish that task.

WARNING!: If you change the buffer length and read in a backup file then if the new buffer length is less than the backup data length then data will be lost. Additionally, if you store an archive of the data with a signal file then the different buffer lengths may cause some obtuse anomalies. If you retain state information from run to run then it is best to keep the buffer length fixed.