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2
2.5.4
RS485 Master/Slave
The RS485 master/slave connection is used to build a multi-sided reading system;
there can be one master and up to 5 slaves connected together.
The slave decoders are connected together using RS485 half-duplex on the main
serial interface. Every slave decoder must have a multidrop address in the range 0-4.
The master decoder is also connected to the Host on the RS232 auxiliary serial
interface.
The External Trigger signal is unique to the system; there is a single reading phase
and a single message from the master decoder to the Host computer.
It is necessary to bring the External Trigger signal to all the decoders.
The main and auxiliary ports are connected as shown in the figure below.
DP1200 Master
1
Host
The auxiliary serial interface of the slave decoders can be used in
Local Echo communication mode to control any single decoder
(visualize collected data) or to configure it using the WinHost utility or
Host Mode Programming procedure.
The termination resistors of the RS485 bus must not be installed.
NOTE
28
2
3
1
2
3
Figure 27 - RS485 Master/Slave layout
LSXXXX
reader
Auxiliary serial interface
RS485 HD Main serial interface
External Trigger
DP1200
1
LSXXXX
reader
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