Honeywell ControlEdge 900 platform, Hardware Planning And Installation Manual, Page: 38 / 230

Component
Type
Comments
its slot.
Unmanaged
Switches 900 I/O racks with EPM gateways have been qualified to
communicate with UOC through unmanaged switches. Managed
switches may not be used. For information on qualified switches see
the
ControlEdge 900 Hardware and Installation Guide .
DLR Direct Connection to 900 I/O and EIP devices
DLR is layer 2 data link layer protocol that provides media
redundancy, faster network fault detection, and network fault
resolution in a ring topology. On network with only DLR devices, one
device act as an active ring supervisor and other devices form ring
nodes. DLR network contain a maximum 50 IP address nodes (This is
Honeywell specification).
DLR network should have at least one node configured as ring
supervisor. If there are multiple nodes configured as supervisor, then
the node with highest supervisor precedence value becomes active
supervisor, others will be backup Supervisors. Ring supervisor
connects to CPM through a third party devices.
The active ring supervisor cyclically sends out Beacon Frames and
Announce Frames on both ports. They are received on one port of a
ring node, processed and passed on to the next ring node via the
other port. By default the Beacon Frames are sent every 400
microseconds and the Announce Frames are sent every second.
An example of a DLR Ring network is shown in the following diagram
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