GEMO
INTERNAL LINE TERMINATION CIRCUITRY
AR2-S-24VDC-MB1 has an internal line termination circuitry for the MODBUS RS-485 line that can be activated
easily with an external connection.
Internal line termination circuitry is composed of an “1nF” capacitor connected series with an “120 Ohm” resistor
connected in series. On end of the line termination circuitry is connected to (“-”) pin of MODBUS RS-485
connection internally. The other end is connected to (“LT”) pin for external activation.
In order to activate internal line termination circuitry, simply short circuit (“LT”) pin to (“+”) pin of MODBUS RS-485
line.
Line termination may be required only for the devices at the end of a RS-485 line (2 devices only). Line termination
is not done for the devices connected somewhere in between the two ends.
Internal line termination circuitry may not always give a good result for your application. Please check
communication performance before and after line termination is done.
For details of line termination on an RS-485 MODBUS line, please refer to:
“MODBUS over Serial Line Specification & Implementation guide V1.0, MODBUS.ORG, 12/02/02,
http://www.modbus.org/docs/Modbus_over_serial_line_V1.pdf”
Gürbüzo
ğ
lu Elektronik San. ve Tic.Ltd.
Ş
ti.
http://www.gemo.com.tr
Çamlıtepe Cad. No:297 / 3-4 Siteler, Ankara, Türkiye
e-posta: [email protected]
Tel: 0-312-3503900, Faks: 0-312-3511117
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