Thanks for all the reply. I've checked the source codes, it seems to me that only Apex Destiny 6100 and DSC security system are supported. I was trying to locate the API specification for Apex and others, but I can't find them. The Apex document that was mentioned in the wiki doesn't exist anymore. That would be hard to do anything if we can't get the spec.
I have found that PowerMax is all wireless and we can use serial port to communicate with it, but user manual says that it will only upload and download data through the port, so I'm not sure if we can control it. I also cannot find the spec for this one either.
Does anyone have access to any of these spec? I'm looking for PowerMax, GE Interlogix/Caddx and Apex. If I can get a hold of these, I will try to write driver for it. Otherwise, I might have to re-consider Apex and may be find a way to hardwire at least one keypad to the main board and use orbiters as remote controls in other areas.