Industrial RS485 TTL Converter
Model: TTL-485-2 $42.95 In stock

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The TTL-485-2 is a compact, rugged, industrial-grade, bi-directional RS485 to TTL converter, which can be used to convert 2-wire RS485 to 5V DC TTL-compatible levels and vice versa. This industrial RS485 to TTL converter supports multi-drop RS485 networks and can be used to communicate with one loop of up to 128 units of RS485 devices. It operates within a temperature range of -40ºF to 185ºF (-40ºC to 85ºC), and features 600W surge protection and 15kV static protection. The unit is powered from an external 5V DC regulated power supply (included); it supports data direction auto-turnaround, which automatically enables the RS485 transceiver when data is present on the TTL side. Therefore, it requires no software drivers or flow control, making the unit a highly reliable and truly plug-and-play device. The built-in 120-Ohm terminator (for system reliability and easy installation) can be turned ON or OFF through a simple jumper setting, thus making the device an ideal solution for all types of installations.

CommFront's TTL 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 to ttl converter)

Industrial TTL RS485 Converter
RS485 TTL Converter
TTL RS485 Converter


  • Converts RS485 to 5V TTL and vice versa.
  • External 5VDC powered (included).
  • Industrial grade enclosed in a rugged, rustless ABS housing.
  • Supports multi-drop RS485 networks (up to 128 nodes).
  • 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).
  • Data direction auto-turnaround, no software drivers or flow control is required.
  • Built-in selectable 120Ω terminator for system reliability and easy installation.
  • 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: TTL-485-2
Compatibility: EIA/TIA RS-485 standard and TTL level
Power Source: +5VDC (±5%) Regulated Power Supply (included)
Current Consumption: Less than 30mA
Baud Rates: 300 to 115,200bps (Auto-sensing & Self-adjusting)
Distance: RS485 side: Up to 4000ft (1.2km) at 19,200bps; TTL side: 10ft (3m)
Connector: TTL Side: DB-9 Male; RS485 Side: DB-9 Male; Termination Board (TTL): DB-9 Female and a 3-way Terminal Block; Termination Board (RS485): DB-9 Female and a 4-Way Terminal Block
Maximum number of drops: 128
End of Line Terminator: 120Ω (built-in, selectable)
Surge protection: 600W
Static protection (ESD): Up to 15KV
Dimensions (H x W x D): 0.63 x 1.3 x 4.5 in (16 x 32 x 115 mm) (with Termination Boards)
Weight: 1.66 oz (47 g) (with Termination Boards)
Operating Temperature: -40ºF to 185ºF (-40ºC to 85ºC)
Operating Humidity: Up to 90% RH (no condensation)


TTL Input TTL Output
High (>2.0V) High (5.0V)
Low (<0.8V) Low (0.0V)


TTL Side

DB-9 Male Pin 1 3 5
Terminal Block TX RX GND
Function TTL Out TTL In GND

Note: The TTL side comes with a 3-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.

RS485 to TTL / CMOS 3.3v converter - DB9 and Terminal Block Pinouts
DB-9 Male (view from front) / Terminal Block


RS485 Side

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

Note: The RS485 side 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.

TTL to RS485 converter - DB9 and Terminal Block pinouts
DB-9 Male / Terminal Block (view from front)



TTL to RS485 converter - RS485 bus 120 Ohm end-of-line terminator Jumper settings

Important: Turn ON Jumper 120 (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 is over 660ft (200m).


RS485 to TTL converter, TTL 5v to RS485 converter

Figure 1: Master-Slave Multi-Drop Connections

RS485 to TTL converter, Extend TTL distance

Figure 2: Extending TTL Distance (Half-Duplex)


1) External 5VDC power input

TTL to RS485 converter - external 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 to TTL converter - loopback test

  • Connect two numbers of TTL-485-2 to your PC’s RS-485 COM ports and short TX and RX (TX to RX and RX to TX) on the TTL 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.

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