RS485 Repeater
Model: RPT-485_422-2 $59.95 In stock

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The RPT-485_422-2 is a multi-function, compact, rugged, industrial-grade RS485 repeater / RS422 repeater / RS485 to RS422 converter, which can be used to extend the RS485 or RS422 distance to up to 4000 ft (1.2km), or to convert a two-wire RS-485 signal into a four-wire RS-422 signal, and vice versa. This industrial RS422 / RS485 repeater / converter operates within a temperature range of -40ºF to 185ºF (-40ºC to 85ºC), and features 600W surge protection and 15kV static protection. The device is powered from an external 5V DC regulated power supply (included), and it supports data direction auto-turnaround. Therefore, it requires no software drivers or flow control, making the unit a highly reliable and truly plug-and-play device and an ideal solution for all types of installations.

CommFront's serial converters were strictly certified by SGS and/or TUV (both are the Nationally Recognized Testing Laboratories [NRTLs] in North America (approved by OSHA) and the Notified Bodies in the European Union. CommFront's product quality is ensured by our ISO 9001:2008 (Cert No. SG12/04213) quality control system (strictly certified by SGS/UKAS), and we back our high-quality converter products with a 30-day risk-free money-back guarantee and a 5-year replacement warranty.


PRODUCT PHOTOS (INDUSTRIAL rs485 repeater / rs422 repeater)

RS485 Repeater - RS422 Repeater
RS422 Repeater
RS485 Repeater


  • Extends RS485 or RS422's distance to up to 4000ft (1.2km).
  • Converts 2-wire RS485 to 4-wire RS422 and vice versa.
  • External 5V DC powered (included).
  • Industrial grade enclosed in a rugged, rustless ABS housing.
  • 300 to 115.2K Baud operation (auto-sensing & self-adjusting).
  • Operating temperature: -40ºF to 185ºF (-40ºC to 85ºC).
  • Plug and play (hot-pluggable, data format auto-sensing & self-adjusting).
  • No software drivers or flow controls required.
  • Built-in 600W surge protection, 15kV 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).
  • 5-year manufacturer's warranty.


Part Number: RPT-485_422-2
Compatibility: EIA/TIA RS-485 and RS-422 standard
Power Source: +5V DC (±5%) Regulated Power Supply (included)
Current Consumption: Less than 30mA
Baud Rates: 300 to 115,200bps (auto-sensing and self-adjusting)
Distances: Up to 4000ft (1.2km) at 19,200bps
Connectors: 2x DB-9 Male Connectors; 2x Termination Boards: DB-9 Female and a 6-Way Terminal Block
Surge protection: 600W
Static protection (ESD): Up to 15KV
Dimensions (H x W x D): 0.63 x 1.3 x 4.6 in (16 x 32 x 118 mm) (with termination boards)
Weight: 2.0 oz (57 g) (with termination boards)
Operating Temperature: -40ºF to 185ºF (-40ºC to 85ºC)
Operating Humidity: Up to 90% RH (no condensation)


RS485/RS422 Side

Pin 1 2 3 4 5 6 7 8 4
Jumper J2 (default: ON) J2 (default: ON) J1 (default: ON) J4 (default: ON)
RS485 A+ (J2 ON) B- (J3 ON) GND (J1 ON) Terminate/remove Jumper J4 to turn ON/OFF the 120Ω end-of-line terminator.
RS485 (J2 OFF) J3 OFF) GND (J1 OFF)

Note: This RS485 / RS422 converter / repeater comes with two (2) nos. of 6-way terminal blocks for easy wire connections. However, you may choose not to use the terminal block provided and simply follow the above table for pin assignments.

RS485 RS422 repeater - DB9 and Terminal Block pinouts
DB-9 Male (view from front) / Terminal Block



1) 2-wire RS485 Mode

RS485 RS422 Repater RS485 mode

Turn ON Jumper 1, 2 & 3, and turn OFF Jumper 4 for RS-485 mode.

2) 4-wire RS422 Mode

RS485 RS422 repeater RS422 mode

Turn OFF Jumper 1, 2, 3 & 4 for RS-422 mode.


RS485 Repeater

Figure 1: Two-wire RS-485 Repeater

(Note: The maximum number of supported nodes depends on the RS-485 master)

RS422 Repeater

Figure 2: Four-wire RS-422 Repeater

(Note: The maximum number of supported nodes depends on the RS-422 master)

RS485 RS422 repeater connection

Figure 3: Two-wire RS-485 <=> Four-wire RS-422


1) External 5VDC power input

RS485 RS422 repeater - Power Input

  • CAUTION: Be sure that the DC power applied to pin +5V and GND is within the range of +4.75V to +5.25V (5V ±5%). Excessive input voltage or incorrect polarity connection could damage the converter.

2) Loopback Test

RS485 RS422 repeater extender booster loopback test

  • Connect an RPT-485_422-2 to your PC's RS422 port and remove Jumper 1 and terminate Jumper 2 and 3 on the loopback-side termination board (as shown above).
  • Run 232Analyzer FREE version software on your computer.
  • 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.

RS485 RS422 repeater - loopback test 2
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.


RS-232: 3 easy steps to understand and control your RS232 devices
RS-485/RS422: Building a reliable RS485/RS422 network