Need protobuf decoding in function,how can i do that? and while inserting rows in table from function node getting error as ""message": "column msgtype is required." "type": "validation"'

Protobuf is not supported in the Losant function node.

I answered this on your other thread here:

The time series database, which stores data for device attributes, is the primary source of data for Losant Dashboards. If you want to retrieve the time series data for offline processing or other visualization, it can be exported at any time. I provided details about exported data in your other thread linked above.