Although very similar in design, the role of History Log data is significantly different from Event Log data. Event Log data are designed to facilitate establishing and maintaining consumer's confidence on a meter's operation. For that reason, the implementation of an event logger must comply with strict guidelines and uniform rules consistent with the implementation of an audit trail capable of controlling all meter changes to metrology entities. On the other hand, a History logger provides monitoring capabilities of any meter activity or events that can be of general interest for operators. Both History logger and Event logger may coexist in a meter. To perform a reading of History Logs, execute the next procedures.

1.Write to a Start Read Tag (1, 74, 0, 0) with two Elements with the initial and final date and time to start the transfer process.

2.If needed, monitor the transfer by reading the Status Read Tag (2, 74, 0, 0).

3.When the transfer ends, read the Read Table Tag configured for the ST-74 table on section zero (0, 74, 0, 0) and another Tag on section one (0, 74, 1, 0).

4.To perform an Event Log reading, create the same Tags with the N2 or B2 parameter from the previous steps with the value 76.