sqlSyncHisExpr

This is a tag which must be configured on each sqlConn record used by the connSyncHis() function. The value must be an Axon expression which evaluates to a function with three parameters:

• sqlConn: the sqlConn record
• his: the his-point record being synced
• span: a range of two DateTime values

The function must be return a grid with at exactly two columns for the history data to sync. The first column must be a timestamp in the correct timezone. The second column must be the value. See sql.