What's Next?

With its various modules and an active community, FHEM has become an important tool for open source IoT. However, the FHEM project also faces a number of (minor) problems. In particular, any enthusiast wanting to provide a new module can do so – assuming they follow a couple of rules. Accordingly, both the syntax and quality of the software can vary from module to module. It is not always easy for beginners to understand what commands need to look like.

The FHEM command reference [4] attempts to help by documenting the official modules. However, there are often delays before module changes appear in the command reference, or, in the worst case, changes may only be discussed on the FHEM forum. In case of problems, browsing through multi-page forum threads in the search for a solution may be your only hope.

In order to leverage the enormous possibilities that FHEM offers, it can also be useful to turn to commercial software. FHEM, with its wide range of modules, acts as a gateway between the third-party systems to be integrated on the one hand and a central control unit on the other. Sophisticated logic functions can often be implemented more easily with graphical solutions such as Node-RED or Loxone. FHEM is exclusively text-based, and Perl as programming language limits the possibilities in some cases.

Anyone who has ever failed to get a module to work in FHEM will understand the criticism being levied at the fact that users must resolve the software dependencies themselves. Resolving the dependencies sometimes results in unbelievably long-winded terminal commands needed to integrate the appropriate software versions into the basic system.

When you install a new system, you can quickly lose track of which dependencies have to be manually resolved, since the backup usually only contains the central FHEM configuration files. An automatic installation of the required resources, as in the case of Node-RED or openHAB, would be the easier approach for most users. But when it comes to depth of integration, you would be hard-pressed to find a system that matches FHEM.