MIDAS can either be the “Maximum Integrated Data Acquisition System” used at TRIUMF and PSI or “Multiple Instance Data Acquisition” from Daresbury. They are NOT the same thing at all. As you mention Exogam, I assume you want the latter.
The ISOLDE Decay Station at CERN uses the Daresbury MIDAS and Razvan Lica has written some code to convert into root format: https://github.com/rlica/nutaq4ids which might be what you need. However, IDS only uses a subset of the full Exogam format, so I’m not sure how much Razvan implemented. I know he based it on something I sent him, but that didn’t make trees.