Operating Modes and Character Recognition
6NH7811-0AA22 © Siemens AG 2002 All Rights Reserved
4-20 MD2 Modem (07/2002)
Test Operating Mode "Test send RS485"
The "Test send RS485" test operating mode has the same function as the "Test
send" mode. However, in addition to the sending of a short message over the WAN
interface it is also sent over the RS485 interface. The "Test send RS485" test
operating mode should also be used together with the "Test receive" mode.
Fig. 4-15 shows one possible test configuration for a star network with point-to-
point connection with 2-wire half-duplex. This could also be a multidrop network.
Any other network type using 4-wire full-duplex could also be tested.
In Fig. 4-15 the MD2 modems on the left and the middle are 2-wire terminal points
in a star network. The MD2 on the left is set to "Test send RS485" test operating
mode, the one in the middle is set to "With RS485 interface". The MD2 on the right
is also a 2-wire terminal point but its operating mode is set to "Test receive".
Fig. 4-15 Test configuration for operating mode "Test send RS485"
Operating
mode
"Test receive"
LTOP1
LTOP1
LTOP1
overvoltage
protection
6NH9821-0BC11
2-wire dedicated line
MD2
MD2
RS
485
Cable
6NH7700-2AR60
Cable
6NH7700-2AR60
LTOP1
overvoltage
protection
6NH9821-0BC11
MD2
RS
485
Operating mode
"With RS485
interface"
Operating
mode
"Test send
RS485"
LED RXD:
flashes synchro-
nously to baud
rate
When receive
level ok:
LED RXD:
and
LED DCD:
flash
synchronously
To Next Page
Loading...
