What are the maximum distances allowed for the IO Module bus?


How long and what topology can the IOU bus be on a Netcontroller?

Product Line

Andover Continuum


IOU Modules



Maximum cable distances and topologies required.


The Standard RS485 modules can only be connected in a bus (Daisy Chain) topology, no star or "T" topology can be used.
The maximum distance from the Netcontroller to the last module in the bus is 600M using a low capacitance cable like the Belden 9729.

If you have to create a free topology network with a star or "T" topology then you must use FTT-10A Netcontroller and IOU Modules.

See Lessons Learned #6737 for details on the FTT-10A module wiring or the I/O System Reference Guide for further installation details.