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96 CHAPTER 7: POS TERMINAL ACCESS SERVICE
Figure 40 Dial-up access when the POS access router is located at the commercial client
side
Due to the way POS access service usually operates, that is, low speed, high
frequency and small traffic, it is rather sensitive to the dial-up connection time and
requires the interface board for fast dial-up function. However, the present
common PC modem cannot meet the response time requirements of 10 to 20
seconds. At present, most POS equipment manufacturers use the special modem
chip that supports fast connection to implement the function. The FCM card of
the 3Com Router series is a fast handshaking modem specially designed for POS
dial-up access service.
POS Network Access
In the POS network access mode, the router providing POS access service is
located at the commercial client end and helps all the POS terminals access the
3Com Router series. The router located at the FEP side can be any router and
communicates with the 3Com Router series through X.25, FR, DDN, ISDN or
modem.
The following figure shows the networking of typical POS network access.
Figure 41 Access mode when the POS access router located at the commercial client end
In the POS network access mode, 3Com Router series can be connected to the
POS terminal in the following two ways:
■ Directly connect the POS RS-232 connector with the asynchronous interface
(including the asynchronous mode of the synchronous/asynchronous interface)
of the 3Com Router series. If the distance between them exceeds 15 meters, it
will be necessary to install a long-line-driver at each end of the connection line.
The valid connection distance of a pair of passive long-line-drivers is about
1200 meters.
■ Set up an RS-485 network with the POS terminal device and POS concentrator,
then connect the RS-232 connector of the POS concentrator with the
asynchronous interface of the 3Com Router series. The 3Com Router series
communicate on the egress port in the same way as the first connection
method. Access in this way can save the router interface source greatly.
The advantages of POS network access are as follows:
POS terminal
FCM
Quidway
PSTN/
PBX
PSTN/ISDN
X.25/FR/DDN
Router
UNIX FEP
POS terminal
POS terminal
Router
Router
Quidway
PSTN, ISDN
X.25,FR,DDN
RS-232
RS-232
Serial
port
Ethernet
interface
Long line
drive
UNIX FEP
POS1
RS-485
POS2
POS
concentrator
POS
Router
Router