19/09/18
Page 23 of 67
ASR650 Operational Manual
The two ends of the cable should have a termination resistor connected across the two wires.
Without termination resistors, reflections of fast driver edges can cause multiple data edges that
can cause data corruption. The value of each termination resistor should be equal to the cable
impedance (typically 120
Ω for twisted pairs).
The above drawing shows the RS485 schematic of the ASR650 including the fail-safe resistors
and protection diodes. The resistors are necessary for biasing the lines to known voltages and
nodes will not interpret the noise from undriven lines as actual data.
The RS485 baud rate can be configured from 9600 to 115200 baud. Please ensure that all nodes
use the same and correct setting.
It is very important that each device on the bus uses a different network- or
node address. If several readers are using the same address, data collision
might be the result. You can change the reader’s node addresses via the
ASR-PC-Demo
Software.
4
ASR650 Settings
In order to allow the ASR650 to work in a wide range of applications, there are lots of possibilities
for changing the behavior of the reader, i.e. for altering several settings. Therefore, Agrident
provides a software which is available for free. You may also control the reader with own software
or change settings using the corresponding commands according to the ASR650 protocol. Please
see the ASR650 protocol description for details.
All the different reader settings will be explained in combination with the
ASR-PC-Demo
software
for stationary readers in the following chapters as well as the comprehensive diagnostic
capabilities.
