Honeywell ControlEdge 900R04-0200 Getting Started page 12

Chapter 2 - Overview
Figure 2-1: System architecture for ControlEdge PLC
ControlEdge PLC system has two network levels, while level 1 network
is used for internal I/O communication between CPM and related
IOMs, and level 2 is aimed for the communication with the third party
devices, HMI, SCADA or Engineering Workstation.
On the level 1 network, CPMs and EPMs connect to a switch, this
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. On the level 2
network, the Engineering Workstation, third party devices, HMI, and
SCADA connect to the switch at this level. A failure of this level
network may result in a loss of view of the process if HMI or SCADA is
employed. The two network levels must be isolated with each other.
ETH1/ETH2 ports are required to be protected using a firewall device
configured to prevent uncontrolled messages into the controller.
Built-in firewall is supported on CPM of ControlEdge PLC.
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