Xerox WorkCentre Pro 423 Service Manual Download

Page: 135 / 619

03/02

Level 2 Troubleshooting

WorkCentre Pro 423/428

2-103

CHAPTER 2 TROUBLESHOOTING

2.3.2.8 Installation notes

Several terminals on a single ISDN line (Bus connection)

NET64 allows the connection of up to eight terminals to a line through a bus. However, only
two sessions can be established at a time. For bus wiring, note the distance from DSU and
the terminator mounting positions. Since ISDN uses signals of 5.2

m wide, incorrect wiring

may cause signal waveform disorders or errors. Different errors may occur only in a specific
device connected to the bus, or the same error may occur frequently.

The maximum distance is prescribed because the line distance increases the loss as the
distance from DSU becomes long. The maximum distance is within 750 m when one
terminal is connected but within 150 m when several terminals are connected. However,
these lengths apply to cables of 0.5 mm in diameter. A thinner cable has greater resistance.
This resistance increases the line loss and reduces the maximum length.

A four-core paired-wire cable is used for wiring between MJs.  In this case, all terminals must
have the same polarities.   The polarities are TA (MJ pin 3), TB (MJ pin 6), RA (MJ pin 4), and
RB (MJ pin 5).  Pair TA with TB and also RA with RB by checking the cable wire colours and
patterns.  When using an 8-core cable, pair pins 1 and 2 and also pins 7 and 8. (A 10BASE-T
cable for LAN has different pin numbers. To prevent errors, do not use a 10BASE-T cable.)

Install a terminator only to the farthest connection block or terminal from DSU. If two or more
terminators are attached to a single line, the combined resistance goes down and may cause
signal waveform disorders and communication errors.

Many TAs or routers now in the market have built-in terminators that are turned OFF and ON
by switches. Terminals may also have built-in terminators. When connecting these terminals
by bus wiring, check the built-in terminators and leave the terminator alive only in one unit or
install one to the connection block of the farthest terminal.

If terminals are connected to the S/T point (explained later) of a TA/router with built-in DSU
and the connection distance is very long, turn OFF the terminator of the TA/router and install
a terminator to the farthest terminal. If the terminator of the TA/router is left ON and no
terminator is installed to the connection point of the cable from the S/T point, signals may
become unstable and result in errors because the long line is not terminated.

For reception only at a specific terminal among the ones connected through a bus, set a dial-
in number to each terminal by concluding a dial-in service contract with (charged service) or
a subaddress to each terminal by no contract (free service). Then notify the transmission
side of a terminal-unique number (dial-in number or telephone subaddress). Be
sure to set "Communication capability (TEL/G4/G3) to a G4/G3 fax where a dial-in number or
subaddress is registered. Select a terminal type(s) for communication.

Dial-in contract line

A general public telephone line always has a telephone number (contractor line number).  Te
dial-in service allows several telephone numbers to be added to a line (up to 8 lines to a
NET64 line).  (The numbers are called dial-in numbers or subnumbers.)  If eight terminals are
connected to NET64 and eight dial-in numbers are registered to the terminals, a calling
terminal can specify a terminating terminal. If terminals of different communication types are
connected by bus wiring, the dial-in service prevents all the terminals from ringing.
If a call terminates at a terminal of the dial-in service, the network gives information about the
termination number. A terminal with a dial-in number receives a call only when the
termination number from the network matches its dial-in number. If the same number is
registered to several terminals, a call terminates at all the terminals.  (However, such a call is
usually received at the nearest terminal to DSU.)
One of the additional dial-in services is "global termination."
Under the contract of global termination, the network does not give number information about
a call terminating with the contractor line number as follows:

Contract

Termination with contractor line

number

Termination with subnumber

(added for dial-in)

Using global termination

Termination number not given

Termination number given

Not using global termination

Termination number given

If a call terminates with the subcontractor line number, all ISDN terminals answer the call
(sending CALLPROC) and the network selects the fastest one (returning CONN). This
reduces the line busy status because all terminals (excluding busy one) answer a call if only
terminals of the same communication type (G4Fax, etc.) are connected through a bus.
Some models of TA/router support "global termination rejection" to their analogue ports.
These models do not allow a call through a global termination line to terminate at ports of
global termination rejection (not sending the alerting signal) if the call does not give a
termination number but the contractor line number. This function prevents several terminals
connected to a TA/router from ringing together and allows a call to terminate only at a specific
terminal.
(Example of use)

Contract number: 567-1000

Subnumber (added for dial-in): 567-1234

TA: Set the dial-in number "5671234" and "global termination rejection" to the port where
terminal B is connected. Do not set anything to the port where terminal A is connected.
Dial-in contract: Using global termination

If a calling terminal dials "567-0000"

⇒

The network does not give number information to the

termination side. In this case, TA does not call the port where terminal B is connected.
However, since the port where terminal A is connected is called, only terminal A rings and
answers the call. Terminal B does not ring.

If a calling terminal dials "567-1234"

⇒

The network gives number information "5671234" to

the termination side. In this case, TA calls the port where terminal B is connected because
the dial-in number "5671234" is registered, but not the port where terminal A is connected. In
other words, terminal B rings but terminal A does not. Thus, the global termination function
can allow termination only at specific terminals.

Xerox WorkCentre Pro 423, Service Manual

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