Acksys MI400 Series, Technical Documentation Manual

Page: 68 / 80

Page B-2
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In RS422 multipoint slave mode or in RS485 mode, the RTS/DTR lamp
remains off.
Check the configuration of SW2, transmission validation by either RTS or DTR.Check that
the serial driver correctly handles the RTS or DTR signal (see the signal-timing
diagram on page 2-5 ). If not, generate the RTS signal with a shunt (configuration n°1
or n°2 on pages 2-7 and 2-8 ), or use the xxMI400/RTS model with automatic
transmission control.
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In RS422 multipoint slave mode or in RS485 mode, numerous transmission
errors.
Check the line bias, only one bias per line is required.
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The lamps operate normally, but no correct replies.
Check the cabling on the RS422A/RS485 connector.
Check the bias of the RS422A/RS485 signals in the idle state. In an idle state, the +TX and
+RX differential signals are at a lower potential than the -TX and -RX signals. This
remark is particularly important when connecting other RS422A-RS485
interfaces. In effect, there is considerable confusion concerning the idle state in
which the line should be found, and concerning the names for sTX, +RX, -
TX and -RX (A, A', B and B') in the various interfaces of different manufacturers.