EFM log files can be large, and many flow meters are Serial or may be located far from the site that is collecting the flow data. As such, narrow bandwidths and the potential for line noise in communications can impact the real-time data collection during file upload.

To ensure timely collection of real-time data from flow meters, EFM-enabled drivers use interleaving to collect both historical and real-time data sets. This interleaving is a 1:3 ratio, with one historical record being requested for every three real-time data requests.

Note: While interleaving, the priority in order of highest to lowest is as follows: writes, reads, and exception-based reads. EFM polls are considered reads.