It seems that the eMachineShop CAD modeling tool supports the export to standard DXF, so it should be quite possible to convert EMS to DXF using it. No other program that would support EMS CAD designs except for eMachineShop is not known to us, so it is likely the only way how to perform this conversion.
Convert eMachineShop CAD design file to AutoCAD DXF Drawing Exchange Format.
We found one software available in the database for this conversion.
Microsoft Windows software - convert ems to dxf on Windows
A CAD modeling tool
Convert from ems file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.