3.3
Understanding The DXP Plus Logical Numbering
Because there are no dedicated station or line ports in the DXP Plus, the system uses an automatic configuration method
to logically number its stations and lines. Automatic configuration occurs after you perform a master clear on the
system.
How automatic configuration works
With automatic configuration, the system does a search for all installed station and line boards in the main and
expansion cabinets, and assigns a logical number for each provided station and line encountered during the search. The
search begins in the main cabinet at the left-most universal slot and proceeds left to right. The search then moves to the
upper expansion cabinet where it searches left-most slot to right-most slot. The search finally moves to the lower
expansion cabinet where it again searches left-most slot to right-most slot. When automatic configuration is finished,
the system has logically numbered all station and line ports in ascending order from the left-most slot to right-most slot
throughout the entire system.
How logical number and physical location relate to one another
The logical number of a station or line corresponds to its relationship to other stations or lines in the system but is not
dependent upon the board’s placement in the cabinet. The physical location of a station or line corresponds to the order
of the system’s board slots. The main cabinet contains slots 1–9, the upper expansion cabinet contains slots 10–20, and
the lower expansion cabinet contains slots 21–30. Therefore, even if the first encountered station board is located in
slot five of the main cabinet, the system still assigns logical number one to the first station provided by that board.
During installation, you can skip slots. For example, you can install eight-line, loop start, line boards in only slots one
and 30 if you wish. In this case, slot one yields logical line numbers 1–8 and slot 30 yields logical line numbers 9–17.
Where you can place circuit boards
Each installed board requires timing circuits equal to its capacity. For example, a 16–station board requires 16 timing
circuits, an eight–line loop start line board requires eight circuits, and a fully configured T1 trunk board requires 24
timing circuits. In the DXP Plus, each universal slot provides 32 timing circuits. Because of this timing circuit provision
of each slot, you can place any station or line board at any slot location with no restrictions.
Adding boards without renumbering
If you install or relocate a station or line board, this board does not operate until you take appropriate programming
action. If you use an available open slot for adding or relocating a board, that board’s stations or lines assume logical
numbers in sequence after the system’s last assigned logical station or line number. For example, if the system’s last
logical station number is 24, the logical numbers of the newly installed board’s stations begin at logical number 25.
After you remove a board and delete it through programming, that board’s logical numbers are available for
reassignment. This means that you can remove a board, add or move another board, take the appropriate programming
action, and have the stations or lines of the added or relocated board assume the logical numbers made available by the
removed board. For example, if the system’s last logical number is 64 and you remove the board providing stations with
logical numbers 1–16 and delete it through programming, the stations on an added board assume logical numbers
beginning with 1 instead of 65. However, if you remove and program delete an eight-station board and add a 16-station
board, the first eight stations stations on the added board assume logical numbers 1–8 and the last eight stations assume
logical numbers 65–72.
Remember, should you master clear the system, the automatic configuration feature logically numbers all station and
line ports in ascending order from the left-most slot to right-most slot throughout the entire system. This action
renumbers those station and lines provided by boards that you have added or relocated since you last performed the
system master clear.
3.3.1 Understanding Station Pairing
Station ports are paired ODD/EVEN, beginning with the lowest directory number 101/102, 103/104, etc., for data
and for overload protection. The odd port is the positive voltage (+) port and the even port is the negative voltage
(-) port.
Installing The Digital Station Board
IMI89–174
Installing The Digital Station Board – 9
