Honeywell ControlEdge 900R04-0200 Getting Started page 13

Chapter 2 - Overview
Figure 2-2: System architecture for ControlEdge RTU
ControlEdge 2020 system has two networks, I/O network is used for
internal I/O communication between CPM and Expansion IOMs,
control network is aimed for the communication with the third party
devices, HMI, SCADA or Engineering Workstation.
I/O network is the most critical network in the system as a failure or
loss of service on this network can result in loss of control.
At control network, Engineering Workstation, third party devices, HMI,
and SCADA connect to the switches. A failure of this level network may
result in a loss of view for operator of the process if HMI or SCADA is
employed.
The two networks must be isolated from each other.
13