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CPP100
SECTION 7
CPP1OPS
25/10/06
www.snellwilcox.com
Version 1 Issue 6
7.2
Network Configuration
If a number of Snell & Wilcox products are to be
connected to a RollCall
TM
network each needs to
be assigned a unique identification number. This
Network Address
is a number between 1 and 255
(usually shown in hex as 0x01 to 0xff). Addresses
in the range 0x01 to 0x1f are reserved for network
bridging and gateways so each Prefix must have a
unique address between 0x20 and 0xff.
The best way to configure a network is to draw up
a table of units and allocate an address and name
to each. Each unit should then be set up before
connecting to the network or while the other
devices on the network are powered off.
Alternatively advantage can be taken of the
automatic network address selection facility of the
Prefix. Whenever a Prefix is powered on it checks
that its network address is not already being used
by another device. If the address is being used it
will search for the next available value and will
configure itself to use this new address.
When a new Prefix is delivered to a customer it will
have the factory default network address of 0x20
and network name “PREFIX (20)”. If this unit is
added to a network that already contains a device
with address 0x20 the new unit will pick the next
free address, say for example 0x34. In this case
the unit’s network name will also be updated to
“PREFIX (34)”. The name can now be changed to
something more meaningful.
If a large number of new Prefixes are to be formed
into a network they will all start with address 0x20,
but the second unit to be powered on will find that
0x20 is in use by the first and so will set its address
to 0x21. The third unit powered on will find both
0x20 and 0x21 in use so will select 0x22 and so on
until all units have configured themselves. A
remote control device on the network will show
units named “PREFIX (20)”, “PREFIX (21)”,
“PREFIX (22)” etc. Knowing the order power was
applied will allow each unit to be identified and
more meaningful name, such as “OB Feed 1” or
“Rack 1, Unit 3” to be set. Once a unit’s address is
correctly configured it will not change unless it is
powered off and then attached to a new network
that already has a unit with the same address.
If you wish to configure a network automatically it is
important to realise that each time a Prefix checks
a prospective network address it takes a second.
This means that when configuring a network of 20
devices, each Prefix should be allowed at least 20
seconds to pick a network address before another
unit is powered on. A more accurate method is to
wait for each new Prefix to be shown on a remote
control device such as a
Shoebox
or a PC before
powering on the next one.
Note
: It is not recommended to connect more than
25 Prefixes or other RollCall
TM
devices on a single
section of coax network. If a larger system is
required sections of up to 25 units should be built
with at least one Shoebox each. The sections can
then be linked with 9-way ribbon cable linking the
Shoeboxes’ “Network” connectors. The sections
will all be regarded as one network so any of the
units can be controlled by any of the Shoeboxes.
The total number of units that can be connected in
this way is limited, by the number of unique
addresses, that is, up to about 200.