M-Bus is a standard for remote reading of consumption meters (e.g. water, heat, electricity meters, etc.). As of today, the standard is maintained by OMS-Group, and evolved to support other device types, including sensors, detectors, controllers, etc.
A data frame sent over M-Bus from one device to another is called a datagram (it is also referred as a telegram in M-Bus protocol specification). This page allows you to decode M-Bus datagram using tmbus JavaScript (ES5) library. The library is created primarily for embedded devices with limited storage, but despite its compactness, it is capable of decoding all data from consumption meters.