Data acquisition from Energy Meters

We have 4 energy meters namely: Line-1, Line-2, Generator-1 and Generator-2 All these meters communicate using MODBUS protocol. We wish to fetch data from these meters and store it in a local MS-SQL database housed in a local server PC. We should be able to access this database. In addition, i) In case of power shutdown of the local server PC, no data loss should be there i.e. the software should be able to retrieve data and store it in the database even for the time period when the PC was shut down. This is a critical requirement. We would provide make and model no of these meters. However, we can provide a memory map for only two of the above meters.