Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 72)

Publication 1757-UM006A-EN-P - May 2002
2-28 Integrating Fieldbus into Rockwell Automation Logix System
Tags, Addresses, and Live
List Tag and address assignments
Before a fieldbus device can actively join a network it must be
assigned a name and data link address. Device names are system
specific identifiers called physical device tags (PD_TAG).
The PD_TAGs may be assigned by the vendor or through the System
Management Kernel (SMK), normally in an off-line configuration
environment so devices without tags are kept off the operational
network.
The SMK for devices without tags are set to the Uncommissioned state
and connected to the bus at one of four default device addresses. The
Data Link Layer specifies these default addresses as non-visitor node
addresses. The following figure shows the general allocation of data
link layer addresses to field devices.
Figure 2.10 Summary of address allocations for fieldbus devices
0 10 X Y F8 FB FC FF
Node
Addresses:
Standard, Global,
and Flat Node
Addresses
Usable
Addresses
Usable Addresses
First Unused
Node Address
V(FUN)
Number of
Unused Node
Addresses
V(NUN)
Non-Visitor addresses,
used as default
addresses for devices
requiring address
assignments
Visitor addresses
used for temporary
(handheld) devices
ATTENTION
!
Temporary devices such as handheld interfaces are
not assigned tags or addresses. They join the
network through one of four data link visitor
addresses reserved for them in the data link layer
protocol.