Industrial Port-Powered Isolated RS232/RS485/RS422
Converter
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Model:
CVT-485_422-3
$69.95
In stock
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The CVT-485_422-3 is
a compact,
rugged,
industrial-grade,
optically-isolated,
port-powered, bi-directional
RS232 to RS485 / RS232 to
RS422 converter, which can be used to convert any standard
unbalanced RS232C port into a two-wire half-duplex balanced RS485 port or a
four-wire full-duplex balanced RS485/RS422 port and vice versa.
This
industrial opto-isolated RS232 to RS485/RS422 converter
operates within a
wide temperature range (-40ºF
to 185ºF /-40ºC to 85ºC), features 600W surge protection and
15kV static protection, and comes with
a built-in 120-Ohm terminator
for system reliability and easy
installation.
It also features opto-isolation circuitry, which effectively
protect your RS-232 devices from
ground
loops, noise problems, transient surges, remote lightning and spikes.
The unit is efficiently powered from the RS232 data line; it also supports data
direction auto-turnaround, which automatically enables the
RS485 transceiver when data is present on the RS232 side.
Therefore,
it requires no external power, software drivers
or flow control, making the unit a highly reliable and truly plug-and-play device.
The built-in 120-Ohm
terminator can be turned ON or OFF through a simple jumper
setting, thus making the unit an ideal solution for all
types of installations.
The unit is backed by our 30-day risk-free money-back
guarantee and 5-year replacement warranty.
Baud
rates: 1.2K to 38.4K Baud.
datasheet | FAQs |
product selection guide
rs485/rs422 application note
testing
info |
declaration
of conformity
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PRODUCT PHOTOS
(ISOLATED RS232 TO RS485 RS422 CONVERTER)
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FEATURES (ISOLATED RS232 TO
RS485 / RS232 TO RS422 CONVERTER)
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- Converts RS232 to 2-wire RS485, 4-wire RS485 or 4-wire RS422 and vice versa.
- 1.2K to 38.4K Baud operation (auto-sensing & self-adjusting).
- Built-in 120Ω end-of-line terminator for system reliability
and easy installation.
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Industrial grade with temperature range of -40ºF to 185ºF (-40ºC to 85ºC),
surge
(600W) and static protection (15kV).
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Port-powered, no external power or
RTS, DTR required.
- Accepts external 5VDC regulated power if the port-power is
insufficient.
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Optical isolation effectively protects your RS-232 devices from
ground loops,
transient surges, remote lightning and spikes.
- Plug and play (hot-pluggable, data format auto-sensing &
self-adjusting).
- Data direction auto-turnaround, no flow control is required.
- No
drivers needed.
- Built-in
surge protection, static protection and circuit
protection.
- Surface Mount Technology manufactured to RoHS and ISO-9001 standards.
- Safety: Strictly certified by TUV (Cert No. SG-CE-090012).
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5-year
manufacturer's warranty. |
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SPECIFICATIONS (ISOLATED RS232
TO RS485 RS422 CONVERTER)
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Part Number: |
CVT-485_422-3 |
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Compatibility: |
EIA/TIA
RS-232C standard and RS-485/RS-422 standard |
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Power Source: |
Port power
from RS232 data line |
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Current
Consumption: |
Less than
10mA |
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Optical
Isolation: |
2500Vrms
(AC, 1 min) |
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Baud
Rates: |
1,200
to 38,400bps (auto-sensing & self-adjusting) |
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Distance: |
RS-232 side:
16 ft (5m); RS-485/RS-422 side: Depending on power from RS232
port, will transmit up to 4000 ft (1.2km) at 19,200bps |
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Connector: |
RS232 Side:
DB-9 Female; RS485/RS422 Side: DB-9 Male; Termination Board:
DB-9 Female and a 6-Way Terminal Block |
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Maximum number
of drops: |
64 |
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End of Line
Terminator: |
120Ω
(Built-in) |
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Surge protection: |
600W |
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Static
protection (ESD): |
Up to 15KV |
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Dimensions (H
x W x D): |
0.63 x 1.3
x 3.5 in (16 x 32 x 90 mm) |
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Weight: |
1.37 oz (39
g) |
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Operating
Temperature: |
-40ºF to
185ºF (-40ºC to 85ºC) |
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Operating
Humidity: |
Up to 90%
RH (no condensation) |
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CONVERTER CONNECTOR / TERMINAL
BLOCK PINOUTS
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RS232 Side |
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Pin |
1 |
4 |
6 |
7 |
8 |
2 |
3 |
5 |
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Signal |
DCD |
DSR |
DTR |
CTS |
RTS |
TX |
RX |
GND |
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Function |
Tied |
Tied |
TX |
RX |
GND |
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Note:
Some software requires handshake line
acknowledgements. To satisfy the requirements, our
converter's handshake lines are tied together (DCD,
DTR, and DSR tied together, and RTS and CTS tied
together). Therefore, you don't have to modify your
existing software. |
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DB-9
Female (view from front) |
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RS485 / RS422 Side |
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Pin |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
4 |
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Jumper |
J2
(default: ON) |
J3
(default: ON) |
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J1
(default: ON) |
J4
(default: ON) |
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RS485 |
A+ (J2 ON) |
B- (J3 ON) |
GND |
(J1 ON) |
Terminate/remove Jumper J4
to turn ON/OFF the 120Ω
end-of-line terminator. |
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RS422 |
(J2 OFF) |
(J3 OFF) |
GND |
(J1 OFF) |
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TX+ |
RX+ |
TX- |
RX- |
GND |
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Note:
The CVT-485_422-3 comes with a 6-way terminal block for easy
wire connections. However, you may choose not to use the
terminal block provided and simply follow the above table
for pin assignments. |
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DB-9 Male (view from front) /
Terminal Block |
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JUMPER SETTINGS FOR RS485 /
RS422 MODES AND 120 OHM END-OF-LINE TERMINATOR
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1) RS232 to RS485 Mode |

- Turn ON Jumper 1, 2 & 3 for RS-485 mode;
- Important: Turn ON J4 (120 Ohm End-Of-Line
Terminator) at both ends of the RS-485 bus when the data
rate is over 19.2kbps or the distance exceeds 660 feet
(200m). |
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2) RS232 to RS422 Mode |
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- Turn OFF Jumper 1, 2 & 3 for
RS-422 mode;
- Important: Turn ON J4 (120 Ohm End-Of-Line
Terminator) at both ends of the RS-422 (or 4-wire
RS-485) bus when the data rate is over 19.2kbps or the
distance exceeds 660 feet (200m). |
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CONNECTIONS (RS485 BUS, RS422
BUS, RS232 DISTANCE EXTENSION)
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Figure 1: Master-Slave
Multi-Drop Connections (RS485) |
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Figure 2: Master-Slave
Multi-Drop Connections (RS422)
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Figure 3:
Extending Full-Duplex RS-232
Distance with Opto-Isolation |
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[+]
TROUBLESHOOTING OPTO-ISOLATED RS232 TO RS485 RS422 CONVERTER
1) Port power measurement

Measure pin
+5V and GND with a voltmeter, and be sure that it is around
+5VDC (when RS232 port is connected). 2)
Loopback Test

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Connect a CVT-485_422-3 to your PC's COM port and remove
Jumper 1 and terminate Jumper 2 and 3 on the RS485/422
terminal block (as shown above).
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Run 232Analyzer
FREE version software on your computer.
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Select "ASCII" for both the Send and Receive data
formats. Then send command and/or string such as
"CommFront" from the 232Analyzer software. You should
receive an echo of the command/string sent
("CommFront"). By performing a simple loopback test like
this, you can test both the transmitter and receiver of
the converter. This is very helpful when you are in
doubt about the performance of your converter.

Screenshot: Send/receive
commands from 232Analyzer software.
232Analyzer is an advanced RS232 Serial Protocol Analyzer
software
that allows you to control, monitor and analyze serial port
(RS232 / RS485 / RS422 / TTL, etc.) activities.
Not just the data,
it also allows you to monitor or change RS-232's line
states: RTS, CTS, DTR, DSR, DCD, and RI.
The FREE version (no time
limitation) can be downloaded from
here.
TECH NOTES
RS-232: 3 easy steps to understand and control your RS232
devices
RS-485/RS422:
Building a reliable RS485/RS422 network |
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