The idea is to connect the flow computers (two wire RS-485) to a central hub in remote building(s). I have been told I can connect the flow computers in a star configuration, is this possible, or should they be daisy chained? If star topology is acceptable, where do I place the resistor? The flow computers will then be converted to FO in the remote building(s) and then converted back to hard wire in the control room. I will have multiple FO hubs landing in the control room. I want to connect each one of the hard wired hubs (could be 3 or 4 hubs each with 3 or 4 flow computers) to one RS-485 DCS interface card. Maintaining the requirement of under 32 devices, can this work? Help or direction is appreciated.

 

This seems right. You should have each copper segment in a linear arrangement with a resistor at the beginning and end of each copper segment. In the main location you would have 3 or 4 copper to fiber converters connected via copper to the computer in a linear configuration. The fiber would star out to the remote locations. At each location the converter would be connected to all of the remote devices using a linear copper connection. As always, remember only 1 master at any time, in your case probably the computer.