Bristol Babcock Network 3000 Setup Manual page 23

Chapter 2 - Guidelines For Setting Up BSAP Networks
• A master node can have (using any or all of its ports) a total of 127 slave nodes
on the level below it. If more than this number is needed, the user can consider
using a technique called expanded node addressing (also known as expanded
BSAP or EBSAP) which is discussed fully in the ACCOL II Reference Manual
(document# D4044). Expanded node addressing however, introduces certain
complexities into the network which must be dealt with carefully, and is not
appropriate for all systems. The user should fully understand the implications of
using expanded node addressing, before attempting to use it. In particular, if
you are defining an EBSAP communication line within Open BSI 3.0 (or newer)
the virtual nodes on that communication line must be on Level 1 of your
network, and the expanded addressing slave nodes must be on Level 2 of your
network.
• As you plan your network, you will need to decide whether or not you want to
use data concentrator nodes. Data concentrator nodes are master nodes which
take data from one or more slave nodes, using peer-to-peer communication
(discussed later in this manual) and perform some sort of calculations on that
data; they may or may not have their own local process I/O. Data concentrators
are useful, for example, if control decisions must be made upon data from
several slave nodes. In the illustration on page 2-1, there are 3 nodes which
could potentially serve as data concentrator nodes: DPC1, DPC3, and DPC4.
NOTE: If not configured for peer-to-peer communication, these nodes would
perform whatever local I/O and control they have been configured for, and
simply serve as communication relay devices for their slave nodes, without
making control or processing decisions based on slave node data.
• The local address for a
node is assigned using
jumpers/switches on the
unit (or for some models,
software switches.) That
same address must be
entered for the node in
NETTOP or NetView.
DO NOT use the local
address as a means of
identifying a
name.
For example, if you are designing a network which has a node at each of three
pump stations called pump station #13, #25 and #36, don't set the addresses of
your three nodes to 13, 25, 36. Local addresses should be sequential, and should
always start with address 1. Assigning these values randomly, with gaps in
Network 3000 Communications Configuration Guide
station
Assigning Local Address in NETTOP
Page 2-5