Samsung SSA-P401T, SSA-P400T user manual installation and external connection, Termination Resistor

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 accepted for the communications system.

RS-485/	"		RS-485	RS-485	A
RS-232
Converter	#	120Ω	Termination Resistors	120Ω	B
					SSA-P400(401)

<Termination Resistor in RS-485 Communication>

120Ω

TX+ RX+

RS-422/	TX-	RX-
	RS-422	RS-422
RS-232
	RX+	TX+
Converter	RX-	TX-
	120Ω	SSA-P400(401)
	Termination Resistors

<Termination Resistor in RS-422 Communication>

INSTALLATION AND EXTERNAL CONNECTION

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.

	DC+
	DC-
SSA-P400(401)	Lock/Alarm

Cathode Anode

1N4004 ~ 1n4007 or equiv.

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