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VSE 002 External RS-485 Module
4 RS-485 interface
4
VVSE2/EN M/B006
4. RS-485 interface
The RS-485 interface supports 2-wire connection. The dip switch
S1 is used to switch the termination and signal biasing resistors on
or off.
Termination
ON
OFF
Interface type
TTL
RS-232
Figure 1. Dipswitch positions of VSE 002
The direction control of the RS-485 transceiver is done with the
RTS signal or automatically. The automatic direction control turns
the transceiver to transmit mode after detecting the falling edge of
a 0-bit. The direction is kept in transmit mode for 0,5ms. This
enables the use of the automatic mode with 9,6 kb/s and 19.2 kb/s
speeds. When the transceiver is changed to receive mode, the
RS-485 line changes state to logic 1 state due to the biasing
resistors.