There are 2 different methods to determine the firmware level in a Conzerv EM6400/DM6200/PM1200 meter if there is no communications to the meter: The label on the back of the meter and from the front panel.
Back Label

The firmware revision can be identified by looking at the label on the back of the meter next to "VER"


E.g. This model has a firmware revision of 03.03.05.


Front Panel:

From the front panel, cycle either up or down from the root menu to "DIAG". Once the display reads DIAG, press right and then down to get to "DIA2". Diagnostic screen 2 provides the product model (first line) and firmware revision number (lines 2 and 3).


E.g. This is a EM6400 meter with a firmware revision of 03.02.12.00.