All of our data loggers automatically insert error detection codes into the log memory while they record. When these detection codes for a block of recordings fail the integrity validation, the relevant readings are marked as non validated readings. On your data list, non validated readings are displayed differently to validated readings by default, to indicate that they have failed this integrity test. For the chart, this option can be enabled in the option settings. These error detection codes are saved with the file so any attempts to manipulate data in a saved file are also detected.

There are several reasons why data can be marked as non validated:

• A communication error occurs during data transfer from the Logger to the PC. This is the most likely issue and covers 99% of all cases. When this happens, you can simply download the logger again, and the readings will be displayed correctly. Please ensure the contacts on the back of the logger and the contact pins in the interface cradle are clean.
• Problems occurred during logging where either the readings or the error detection code was not correctly written to memory due to a low battery.
• The logger was operated in an environment beyond the product's operating specifications, for example, extremely hot or cold environments or heavy industrial environment with high electromagnetic fields.

Only in very rare cases is this a result of a memory fault in the logger itself.