DX8200
18
2
RS485 Half-Duplex
The RS485 half-duplex interface (3 wires + shield) is used for polled communication
protocols. It can be used for Multidrop connections in a master/slave layout or with a
Datalogic Multiplexer, (see par. 2.5.3 and 2.5.4).
Device connection to the Multidrop line can be controlled externally through the RS485CNTR
line. For example, it may be necessary to disconnect a scanner from the line if the device is
damaged or the line is overloaded. To do this, apply a voltage from 20 to 30 Vdc to the
RS485CNTR signal using the (A1) GND as a reference.
The following pins of the Main Interface connectors (Figure B, 4 or 5) are used for RS485
half-duplex interface connection:
Connector
Name
Function
25-Pin
9-Pin
7
6
RS485CNTR
multidrop device disconnect
17
2
RS485 transmit/receive data +
5
3
RTX485-
RS485 transmit/receive data -
19
5
GNDRS485
RS485 ground reference
GND
DX8200 9-pin Connector
USER INTERFACE
RTX485-
3
RTX485-
2
GND
5
GNDRS485
RS485GND
Vext
20 to 30 Vdc
RS485CNTR
6
VS
20 to 30 Vdc
±±±±
Figure 16 - RS485 half-duplex interface connections
