Datalogic DS8100A, Reference Manual

Page: 54 / 141

DS8100A REFERENCE MANUAL
40
4
4.2.3 RS485 Half-Duplex Interface
NOTE
This interface is provided for backward compatibility. We recommend using
the more efficient Lonworks network for Master/Slave or Multiplexer layouts.
The RS485 half-duplex (3 wires + shield) interface can be used for polled communication
protocols.
It can be used for Multidrop connections with a Datalogic Multiplexer, (see par. "Multiplexer"
in Appendix A) exploiting a proprietary protocol based on polled mode called MUX32
protocol, where a master device polls slave devices to collect data. The overall maximum
cable length should not exceed 1200 m (3940 ft).
The following pins of the 26-pin connector are used for RS485 half-duplex interface
connection:
Pin Name Function
2 RTX+ RS485 input/output (+)
4 RTX- RS485 input/output (-)
7 GND_ISO Main signal ground
DS8100A
7 GND_ISO
2
RTX485- 4
RS485REF
MULTIPLEXER
RTX485-
1
Earth
Ground
CHASSIS
Figure 49
– RS485 Half-Duplex Interface Connections
This interface is forced by software when the protocol selected is MUX32 protocol.
In a Multiplexer layout, the Multidrop address must also be set via serial channel by the
Genius™ utility or by the Host Programming Mode.
Figure 50 shows a multidrop configuration with DS8100A scanners connected to a
Multiplexer.
CAUTION
This is an example of multidrop wiring. Consult the multiplexer manual for
complete wiring instructions.