There are several third party companies that now support the serial RS-232 data bus protocol coming off the ELK M1. These products include: CQC, MainLobby, PowerHome, mControl, ... plus others.
The M1XEP Ethernet Interface is not required, but it makes the automation package more versatile. You can connect a PC running any of these software packages directly to the M1 through a RS-232 serial port. You will have to keep the M1 within 50 feet of the PC to satisfy the RS-232 specifications. What the M1XEP does give you is the ability to connect a PC anywhere you have internet access to the M1. Once the software has made a Ethernet Socket Connection, the data flowing to the PC is the same as a direct connection using RS-232. The RS-232 direct connection only allows ONE connection. The M1XEP allows up to 30 connections. For example if you have multiple PC's and or Touchscreens, they all need to access the data all the time.
There are four fields of though on home automation controllers:
1. PC controller only - All the control of the home is done by a PC running one of the Automation Software Packages. Downside: Should the PC crash the home automation goes down. You still have to have some kind of hardware to connect to doors, windows, motion detectors, etc.
2. Embedded controller only, like the M1. This is what the M1 was designed to be, the central home automation controller. The M1 is designed with hardware watchdog circuity to stay alive always. Downside: Many of the advanced control and automation desires are beyond the embedded processor on the M1 controller board. Basic home automation functionality is more than satisfied. High level math, speech recognition,... need a PC.
3. PC occasionally connects to the embedded controller ( M1). For remote control and to check on the status of a system, the PC can connect to the embedded controller when desired either through the RS-232 serial port locally or via the M1XEP Ethernet interface any where in the world. The ELKRM Remote Management Software was designed for this purpose.
4. PC constantly connected to the embedded controller ( M1) and running one of the Home Automation Software Packages. This combination give the most advanced home automation control system. The M1 is providing the hardware arms and legs to gather the data required by the PC. Advanced control features can be written for the PC Automation Software. Should the PC lockup or crash, the M1 will continue to execute whatever program it has been given to do. The M1 can even act as a hardware reboot for the PC should communication from the PC fail.