I finally got it working. Few findings to share.
1. My Concord panel was installed by ADT, and my system includes ADT Pulse with Superbus module. However, ADT Superbus does not work with this plugin. I had to get a generic Superbus from eBay. My ADT Superbus module's part number was "59-738-03", and my new generic Superbus was "60-783-02". Thus, if you have a difficult time get this plugin working, check the part number. For some reasons, the ADT Superbus did not work for me.
2. No special programming was needed. I just power cycled (disconnect and re-connect AC and battery) after installing the generic Superbus without removing ADT Superbus. Both Superbus modules works well together. After I confirm everything works well, I will cancel ADT Pulse.
3. My Conord panel is in garage and my Mac is in my office, and no way to run serial cable between two locations. I tried the "RS-232 Extender over CAT 5e" (ref.
https://www.monoprice.com/product?p_id=3598), but it did not work. I tried "TCP/IP Ethernet RJ45 to Serial RS232" (ref.
https://smile.amazon.com/gp/product/B00 ... UTF8&psc=1), and it worked well. Fortunately, I have an Ethernet run in my garage. I think the Ethernet-over-power should work if you don't have any other way to run Ethernet.
4. All door and window sensors work well with the plugin, but I have not figured out how to use motion sensors with this plug in.
I hope this helps anyone who might be interested in using this plugin to Indigo.