If using a Moxa unit, one for each scale, how can address the unit in the 1500S?

I have a similar application from this thread: PLC, HMI, and RS232C., except with a 1500S software controller running on a IPC427E. I have  12 scales. If I use a the Moxa unit, one for each scale, how can I address the unit in the 1500S? Each Moxa unit would go to a Scalance switch. 

Since this is a 1500S application I would also consider reading from the devices directly into Windows  and sharing the data with the 1500S via OPC, is this a viable option? This seems more difficult. 

Thanks for any help with this.

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Split from PLC, HMI, and RS232C.