While waiting for prototype boards from China I'm working on the firmware as well as on a Windows interface. I'll publish the communications protocols later for those who may want to use another OS.
I've decided on two separate designs.
One will be ZX-24 based and will be a revamped version of the Transmogrifier I designed a few years ago. It will use mostly through-hole components and I'll provide a bill of materials for DIY assembly. It will not have the Ethernet interface but will support direct RF or IR input, two TW523 ports, five RS232 ports (one 5V highspeed, four ±12V 9600bps or less), one RS485 port and, depending on the configuration, have a few pins available for ADC or DIO. One RS232 port, one TW523 port and the RS485 port will be mutually exclusive. TW523, RF and IR input are also mutually exclusive but the MR26A and other RF/IR receivers will be supported via RS232. It will supply +5V to power the MR26A. For PLC, it will support 2414S, UPB PIM, CM11A, CPU-XA, Ocelot, Leopard, & TW523 as well as a few other devices. It may require different firmware for RF vs. TW523 support. Cost should be under $100 for the DIY RF version. (Most of the cost is the ZX-24 "chip".)
The other (roZetta) will be PIC based and have six ±12V RS232 ports (one highspeed and five 9600bps* or less) and two TW523 ports. An optional Ethernet port and the highspeed RS232 port are mutually exclusive (but jumper selectable). One lowspeed port can be configured as RS485 or RS232 (jumper selectable). It will use nearly 100% SMD and come fully assembled (except for the Lantastic xPort for Ethernet). roZetta will support the same devices as the Transmogrifier but has no native RF or IR input. It will have seven pins available for ADC or DIO. I think it will cost about $125 (without the xPort "chip") but it's too early to give a firm estimate.
All will be field upgradable, with the ability to download new firmware via the highspeed RS232 port.
I've also designed a generic DIY board that can be used for several PIC based projects. (e.g. Ocelot direct RF input, OS/RS RF weather receiver, serial interface for TW523)
Jeff Volp has offered to make them available through his online store. Jeff will also have cables and other accessories.*It may be possible to do 19200bps but I still need to test that.