X.21 Network Interface - PictureTel Concorde 4500 Servicing Manual

NETWORK INTERFACES

X.21 Network Interface

3-4
Depending on how a network interface is set up, you can have either
a switched or a dedicated network.
A switched network is one in which there is a temporary
connection between two sites for the duration of a dialed call.
A dedicated network, also referred to as a nondialed network, is a
permanent connection between two sites that is on all of the
time.
The ITU-T network interface is widely used in Europe. The X.21
network interface board uses a DA-15P connector for each of two
channel ports to send and receive dialing signals and channel data.
The following cable guidelines must be used when connecting an
X.21 network interface board to the network:
The X.21 network interface transmits data signals and operates
from 56 to 768 kbps for dialed networks and from 56 to 768
kbps for nondialed networks.
For networks at 64 kbps the maximum cable length is 1,200
meters (4,000 feet).
For networks at 768 kpbs the maximum cable length is 250
meters (820 feet).
Use a Belden 9732 (or equivalent) cable.
Provide a DA-15 female connector to mate with the male DA-15
connector on the back of the electronics module (see Appendix
B).
Note: In Enhanced Dialed mode, operation up to 768 kbps is
allocated when using IMUX equipment.
See Appendix C, ÒElectronics Module Connections,Ó for
information on the X.21 network interface panel. Also, see
Appendix B, ÒPin Assignments,Ó for information on pin
assignments.