Revision 10 ControlEdge HC900 Process & Safety Controller User and Installation Manual 19
May 2019
Figure 6 Redundant Configuration with multiple I/O racks (Ring topology)
The ControlEdge HC900-expansion I/O link is a private network and the switch used for the
interconnection of the ControlEdge HC900 Processor and Scanners must not be connected to any other
LAN or WAN. Likewise, no devices other than the ControlEdge HC900 components should be
connected to the I/O link Switch. Failure to comply will cause communication failures on the I/O link
causing I/O modules to go in and out of their failsafe settings.