Instruction manual

This symmetry reflects the way voice channels are used (either side can in-
itiate a call to the other side).
• Valid connection requests originating from the data channel can be made
only by the slave DV-MUX3, because the DV-MUX3 dial-up mode is de-
signed to operate asymmetrically with respect to the data channel. This
means that a request for connecting the link to the other DV-MUX3 can be
made only by the slave DV-MUX3.
This asymmetry reflects the way data systems operate: the equipment at the
side of the master DV-MUX3 (Bridge, Front End Processor, etc.) is assumed
to operate continuously, so that it is always ready to accept the connection to
the remote equipment (i.e., the equipment at the slave DV-MUX3 side), but
there is no point to maintain the connection when the remote equipment has
nothing to send. This approach is particularly well suited to applications such
as shown in figure 1-1, which are clearly asymmetrical. In the application
shown in figure 1-1, the DV-MUX3 connected to the IBM 37X5 must be
configured as the master.
Conditions for
Disconnection of
Main Link
The disconnection of the main link can be initiated only by the slave DV-MUX3.
The disconnection is performed after both voice channels (on both DV-MUX3
units) are inactive and the DTR line in the slave data channel interface is OFF con-
tinuously for a period of 25 seconds.
The disconnection may also be initiated if the synchronization is lost for two sec-
onds. This operation can also be performed by the master DV-MUX3.
Dial-up Modem
Settings
Before starting the operation, the dial-up modems serving the main link must be
configured as follows:
• Synchronous operation.
• Timing modem source:
°
Modem connected to the master DV-MUX3: internal clock.
°
Modem connected to the slave DV-MUX3: loopback timing (that is, its
transmit timing must be locked to the recovered receive clock).
• Error correction and compression functions disabled.
• DTR dialing mode operation (DTR option 108.1).
• Program the directory number to be dialed by each modem.
• Configureeach modem for switching to the originate mode upon assertion of
the DTR line, and for switching to the answer mode upon detection of active
RI line (that is, a modem must dial the preprogrammed number when the
DTR line is asserted; if the DTR line is not asserted, the modem must answer
automatically when the RI line is asserted).
• Thedisconnectiontime followingthe deassertion of the DTR line must beset
to 50 msec.
NOTE
Correct clock source selection is essential for proper operation
of the DV-MUX3. If the timing is not correctly selected, the
DV-MUX3 may periodically lose synchronization.
CHAPTER 1 - INTRODUCTION
1-10 DV-MUX3 Installation and Operation Manual