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1. Overview
USB interface is gradually replacing the old-fashioned low-speed peripheral interfaces of PC with the continuous
development of PC industry. But many vital devices in current industrial environment is still designed using
RS-485/RS-422 interface, so the USB to RS-485/RS-422 converters are needed to transfer data between PC and
RS-485/RS-422 devices.
UT-861 is a universal USB/RS-485/422 converter which doesn’
t need external power supply and has built-in
opto-isolator and DC/DC power isolation module. It is compatible with USB ,RS-422 and RS-485 standards, and
it can convert single-end USB signal to balanced differential RS-422 or 485 signal. The built-in photoelectric
isolator can provide isolating voltage up to 2500Vrms and it equips with high-speed transient voltage supressor
which is designed to protect the RS-422/RS-485 interface. The advanced TVS (TRANSIENT VOLTAGE
SUPPRESSOR) presents high-impedance state under normal conditions, and it can rapidly decrease the resistance
between its two ends while it’
s withstanding transient high-power impulse so as to absorb the high current and
clamp the voltage across it to a preset value, and then the following components will not be damaged by the
transient high-voltage impulse. This suppressor can effectively restrain lightning and ESD (electro-static discharge)
with lightning surge protection power of 600W for each line, and it also can restrain surge voltage and transient
over-voltage on the lines for any reason. Extremely small interelectrode capacitance ensures high speed data
transmission of RS-422/RS-485 interface.The RS-422/RS-485 end is connected through male DB9 connector.It
has built-in automatic transmit-receive switch without time delay. The unique I/O circuit can be used to
automatically control the direction of data flow without any hand-shaking signals(such as RTS and DTR) and
full-duplex(RS-422) and half-duplex (RS-485) can be implemented without jumper configuration,so as to make it
plug-and-play and applicable to all existing communication software and interface hardware.
UT-861 industrial photoelectric isolated interface converter can provide reliable connection for point-to-point or
point-to-multipoint communication. Maximum 128 RS-422 or RS-485 interface devices can be supported for the
point-to-multipoint communication. Data communication rate can be 300-128000BPS, and the power indicator
light and data traffic indicator light can be used for malfunction indication. USB to RS-422 and USB to RS-485
conversions are supported.
2. Main Features
Following communication modes are supported by UT-861 interface converter:
1) Point-to-point/4-wire full-duplex
2) Point-to-multipoint/4-wire full-duplex
3) Point-to-point/2-wire half-duplex
2) Point-to-multipoint/2-wire half-duplex
When the converter is connected for full-duplex or half-duplex communication, a matching resistor (120
Ohm,1/4W) should be connected to the wire terminal for avoiding signal reflection and interference.
3. Hardware Installation and Application
Please read this manual thoroughly and connect the USB cable to the USB port of computer before the installation
of UT-861 interface converter. USB/DB9 connectors are adopted for the input/output terminal and twisted cable or
screened cable can be used. RS-422 or RS-485 communication mode can be implemented without any
configuration and the connection and disassembly are very convenient. T/R+ and T/R- represent transmit and
receive A+/B-, RXD+/RXD- represent receive A+/B-
，
GND means common ground. T/R+ and T/R- should be
connected for point-to-point, point-to-multipoint half-duplex communication, and T/R+
、
T/R-
、
RXD+
、
RXD-
should be connected for point-to-point, point-to-multipoint full-duplex communication.
