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System Installation
Ascom Paging System
• Use only twisted-pair wiring for extension of the system bus.
• Maximum length is 3 km for data buses. Distances exceeding this require modems.
1.3
Data Buses
The A-bus and B-bus are used for data communication between the modules and the D-
bus for communication between Central Unit and Terminal transmitters. The A-, B- and D-
buses carry constant communication.
This can be seen on an oscilloscope as a pulse train. The normal level is 8-10 Vp-p
measured from A1 to A2, B1 to B2, and D1 to D2.
If several units are connected to the buses or if the lines are long, the level will be lower
but must be at least 0.6 Vp-p. The data buses are polarized.
The four data buses (A, B, C, and D) use balanced lines and operate according to EIA
standard RS-485 and CCITT recommendations V.11 and X.27.
• A- and B-buses are identical and are used for connection of interface modules.
• C-bus is used for connecting Central Units together in a multi-central system.
• D-bus transmits pagings in transmit format from the Central Unit to one or several
Terminal Transmitters. It is used when paging functions are to be used in the Ascom
Paging System.
1.4
FL-bus
The FL-bus is a one-way bus to Terminal transmitters. It is used in frequency locked
systems, when transmitters need to be synchronized in overlapping areas.
1.5
Wire Type
Only twisted-pair cables are to be used. Suitable types are, for example EKKX 4 x 2 x 0.5 or
EKKX 10 x 2 x 0.5.
1.6
Wiring Lengths
Max total wiring lengths are:
A-bus
3000 m
B-bus
3000 m
C-bus
3000 m
D-bus
3000 m
FL-bus
3000 m
R-line
1000 m
1.7
Extended Wiring Lengths
If max wiring lengths of the data buses A, B, C and D exceed 3000 meters, or if there are
more than 32 units on a bus, the data bus signal must be amplified. On private lines the
Bus Converter is used, and on leased lines (or very long private lines) the Data Modem is
used. The wiring length of the FL-bus may not exceed 3000 meter.
10 October 2013 / Ver. D
Data communication between modules
Data communication between modules
Data communication between systems
Data communication from central to terminal transmitters
One-way Frequency Lock-bus to terminal transmitters
Data between fixed receiver and receiver interface
TD 90227GB
2
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