Operating Modes and Character Recognition
6NH7811-0AA22 © Siemens AG 2002 All Rights Reserved
4-14 MD2 Modem (07/2002)
Note
The modem does not continuously output the upper keying frequency to the WAN
port. The lower frequency is also output for the period of 1 bit length every 63
bits.
The reason for this is that with continuous output of the upper keying frequency
the refresh logic cannot guarantee that the "RxD" LED of the receiving modem
will light continuously.
The following illustration shows the setting on the 10-pin DIL switch of the MD2 for
the "Test f
H
" operating mode.
Fig. 4-9 DIL switch setting for the
"Test f
H
" operating mode
Note
In order to obtain a complete overview of the quality of the 2-wire or 4-wire
dedicated line, you should carry out tests in both the "Test f
H
" and the "Test f
L
"
operating modes. This way it is sure that both keying frequencies for the selected
baud rate are received at the opposite end of the dedicated line being tested,
thereby ensuring error-free data transmission.
Note
Test operating mode "Test f
H
" is not suitable for measuring the level over the
dedicated line. Use operating mode "Test f
H constant
" for making exact
measurements of the level.
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