Operating Modes and Character Recognition
6NH7811-0AA22 © Siemens AG 2002 All Rights Reserved
4-18 MD2 Modem (07/2002)
Test Operating Mode "Test send"
Similar to the operating modes described previously, the "Test send" test operating
mode can be used to determine the quality of a 2-wire or 4-wire dedicated line by
measuring the attenuation characteristics in relation to the baud rate. In this mode,
however, character strings are sent to check the general functions of the modem
during data transmission. The "Test send" test operating mode should be used
together with the "Test receive" mode.
Fig. 4-13 shows one possible test configuration for a point-to-point connection with
2-wire half-duplex. This could also be a multidrop or star network. Any other
network type using 4-wire full-duplex could also be tested.
In Fig. 4-13 the MD2 on the left is a 2-wire terminal point and is set to test
operating mode "Test send"
. The MD2 on the right is also a 2-wire terminal point
but its operating mode is set to "Test receive".
Fig. 4-13 Test configuration for operating mode "Test send"
LTOP1
overvoltage
protection
6NH9821-0BC11
LTOP1LTOP1
LTOP1
overvoltage
protection
6NH9821-0BC11
2-wire dedicated line
MD2
MD2
Cable
6NH7700-2AR60
Cable
6NH7700-2AR60
Operating
mode
"Test send"
Operating
mode
"Test receive"
LED TXD:
and
LED RTS:
flash synchronously
to baud rate
When receive
level ok:
LED RXD:
and
LED DCD:
flash synchronously
to baud rate
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