Connecting The Termination Resistor And Diode - Samsung SSA-P102 User Manual

installation and external connection

CONNECTING THE TERMINATION RESISTOR AND DIODE

Termination Resistor
A resistor is inserted for matching the line's impedance to prevent distortion and reduction in RS-422 or RS-485
long distance data communications, which is referred to as termination resistor.
Note that termination resistors of lower than 90— are not allowed, neither more than one termination resistor is
accepted for the communications system.
RS-485/RS-232
Converter
RS-485/RS-232
Converter
120Ω
Bypass Diode Connection
If you connected an inductor (door lock or alarm device) to the output relay, there should occur a voltage surge
while the inductor was between turning on and turning off. If you do not connect a bypass diode to the relay, the
voltage surge will cause damage to the electric circuit of the controller. To reduce this surge, it is recommended to
connect a bypass diode to the relay.
SSA-P102
10_
installation and external connection
RS-485
120Ω
Termination Resistors
<Termination Resistor in RS-485 Communication>
TX+
TX-
RS-422
RX+
RX-
Termination Resistors
<Termination Resistor in RS-422 Communication>
DC+
DC-
Lock/Alarm
A
RS-485
B
120Ω
120Ω
RX+
RX-
RS-422
TX+
TX-
Cathode Anode
1N4004 ~ 1n4007 or equiv.
Last SSA-P102
Last SSA-P102