RS232 to RS485 Converter

The CVT-485-1 is an industrial-grade (wide temperature range with surge & static protection) port-powered bi-directional RS232 to RS485 converter, which can be used to convert any standard RS-232C port into a two-wire RS485 port and vice versa.

This industrial-grade RS232 to RS485 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 easy installation.  The unit is powered from the RS232 data line, it also supports data direction auto-turnaround, and therefore, no external power or flow control is required.

Declaration of Conformity | RS232 to RS485 Converter data sheet

FEATURES (INDUSTRIAL RS232 TO RS485 CONVERTER)

- Converts RS232 to 2-wire RS485 and vice versa.
- Industrial grade with wide temperature range (-40ºF to 185ºF / -40ºC to 85ºC),
  surge (600W) and static protection (15kV).
- Port-powered, no external power or RTS, DTR required.
- Plug and play (hot-pluggable, data format auto-sensing & self-adjusting).
- Data direction auto-turnaround, no flow control is required.
- Built-in surge protection, static protection and circuit protection.
- Built-in 120Ω end-of-line terminator for easy installation.
- Surface Mount Technology manufactured to ISO-9001 standards.
- CE certified: strictly certified by world-class lab TUV.
- 5-year manufacturer's warranty.    

PRODUCT PHOTOS (INDUSTRIAL RS232 TO RS485 CONVERTER)

SPECIFICATIONS  (INDUSTRIAL RS232 TO RS485 CONVERTER)

CONVERTER CONNECTOR / TERMINAL BLOCK PINOUTS

RS232 Side

Pin 1 4 6 7 8 2 3 5 Signal DCD DSR DTR CTS RTS TX RX GND Function Tied Tied TX RX GND

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.

DB-9 Female (view from front)

RS485 Side

Pin 1 3 5 9 6 7 Terminal Block A+ B- GND +5V Jumper (120) Function RS485+ RS485- GND +5V measurement Terminate/remove Jumper 120 to turn ON/OFF the 120Ω end-of-line terminator.

Note: The CVT-485-1 comes with a 4-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.   DB-9 Male (view from front) / Terminal Block

120 OHM END-OF-LINE JUMPER SETTINGS

IMPORTANT: Turn ON Jumper 120 (120 Ohm End-Of-Line Terminator) at both ends of the RS-485 bus.    

CONNECTIONS (RS485 BUS, RS232 EXTENSION)

Figure 1: Master-Slave Multi-Drop Connections

Figure 2: Extending Half-Duplex RS232 Distance (Data Only)

TROUBLESHOOTING INSTRUCTIONS FOR RS232 TO RS485 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). Otherwise, please check the power on the RS232 port to which the converter is connected (as shown below).

Note: CommFront port-powered converters require a -7 to -15VDC on the TX line (Pin 3 on DTE or Pin 2 on DCE) of the RS232 port to which the converter is connected. You can connect CVT-485-1 to a DTE device which comes with a DB-9 male connector; however, if it is a DCE device, you will need to swap Pin 2 and 3 before connecting to the converter.

2) Loopback Test

Connect two numbers of CVT-485-1 to your PC’s COM ports and connect A+ to A+, B- to B- on the RS485 terminal blocks (as shown above). Run two instances of the 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 one COM port. You should receive an echo of the command/string sent ("CommFront") on the other COM port. 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 1: Send commands from 1st instance of the 232Analyzer software.

Screenshot 2: Receive commands from 2nd instance of the 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.