Allied Data Technologies TRON SECURE 33.6, Руководство пользователя

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1.6 Originate and answer
It is necessary to make agreements which modem uses which tone sets. For this purpose, the
terms “originate” and “answer” are used. The modem that builds up the connection, sticks to the
originate tones, the other one uses the answer tones. The originate modem sends as agreed with
the low tones and the answer modem with the high tones.
For a backchannel connection, this means that the originate modem sends with the low baudrate
and the answer modem with the high baudrate.
With a full duplex connection, both modems use the same baudrate and the tones for “0” and
“1”are different.
1.7 The modem is transparent
We have seen how the two computers can be connected with each other and how the
communication takes place. When a connection has been established, it is possible to send data
between both computers. The modem only serves to establish the connection, after that they are
fully transparent.
Nevertheless, sometimes communication can go wrong.
If you get “strange”characters on the screen during a connection with a data base, the setting of
the communication program will have to be changed, for example the number of data bits, the
parity bit, or the baudrate. This problem is not caused by the modem. The modem functions as a
hatch.
With Prestel systems (like Videotex), one has to use a program that is especially meant for the
graphical Videotex characters. The fact is, Videotex does not work with the standard ASCII
characters, but it has its own character set. Therefore, strange characters will appear on the
screen if you refer to Videotex with a program which is meant for ASCII.
TRON SECURE 33.6
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