Dp need aswer dp questions

What is data timeout ?

Broad question with several specific answers. In General terms, not specific to DP, a certain data packet (or complete data packet) is not being or was not received over a specified time required for processing the solution.
You would need to look at the DP system, and understand through its alarm definition menu, what this alarm is referencing, if that’s your question. Some systems will classify timeout as simply - no data, and some systems go further as far as telemetry alarms - as incomplete data.