Electroline Control Unit IV, Reference Manual

Page: 18 / 146

Product Description Control Unit IV Reference Manual
1-6 529-0004 Ver.3
1.3.3 Subscriber capacity
The Control Unit’s capacity varies from 4,096 to 1,048,576 subscribers (see Table 1-2). The
number of subscribers per group is determined by the tiering system (OBP or multi-tier).
Both systems can handle up to 16,384 groups, but in an OBP system, a group contains 64
subscribers and in a multi-tier system there are 16 subscribers per group. This means that an
OBP system can control up to 1,048,576 subscribers, and a multi-tier system can control up
to 262,144 subscribers.
The second factor that causes the Control Unit’s capacity to vary is the nominal capacity of
the unit (see Table 1-2). Each unit is designed to control a certain number of addresses. For
example, a 32 K unit shipped to a cable operator contains all 32,768 addresses in its memory.
You cannot modify the number of subscribers. Contact Electroline’s sales department if you
would like to obtain a Control Unit with a larger capacity. Note that the time it takes to
refresh the tap status of all subscribers in the network (i.e. the sequencer’s scan time)
increases with the number of subscribers (see Chapter 4).
Table 1-2: Nominal and actual capacity
Nominal
capacity* Actual subscribers
4K 4,096
32K 32,768
128K 131,072
256K 262,144
512K (OBP only) 524,288
1M (OBP only) 1,048,576
* The Control Unit is sold with a nominal capacity expressed in K, which is equal to 1024.
To calculate the actual number of subscribers your unit supports, multiply the nominal
figure by 1024. For units with 1M capacity, M equals 2
20
.