TTL TO RS485 (B)

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Half-Duplex RS485
TTL TO RS485-1.jpg
Full-Duplex RS422
TTL TO RS485-2.jpg

RS485, TTL




TTL TO RS485 (B) is an industrial-grade rail-mounted electrically isolated TTL-to-RS485 serial converter.


  • Compatible with TTL/RS422 standard, converting the TTL signal into a balanced differential RS422 signal, supporting half-duplex communication
  • Compatible with 3.3V ~ 5V TTL signal level, with anti-reverse connection and anti-over-voltage circuit on the power supply side
  • Onboard unibody power supply isolation, provides stable isolated voltage and needs no extra power supply for the isolated terminal
  • Onboard unibody digital isolation, allows signal isolation, high reliability, strong anti-interference, and low power consumption
  • Onboard TVS (Transient Voltage Suppressor), effectively suppresses surge voltage and transient spike voltage in the circuit, and anti-electrostatic
  • Onboard resettable fuse and protection diodes, ensures the current/voltage stable outputs, provide over-current/over-voltage protection, improve shock resistance
  • On-board RS485 input and output 120R resistors with built-in jumper caps for switching enable
  • Industrial rail-mount ABS case design, small in size, easy to install, and cost-effective


Model Galvanic isolated TTL To RS485 converter
Power Port Power supply 3.3V ~ 5V
Interface Protection anti-over-discharge, reverse-proof
Device interface Compatible with TTL / RS422 standard
TTL Interface Interface type Screw terminal
Transmission distance About 10m
Transmission model Point to point
RS422 Interface Interface type Screw terminal
Interface Protection Provide 600W lightningproof, surge-suppress and 15KV ESD protection
Terminal Resistance 120R, enabled/disabled via switch
Transmission Distance About 1200m
Transmission Mode point-to-multipoint (up to 32 nodes, it is recommended to use repeaters for 16 nodes or more)
Product Appearance Case Rail-mount ABS case, suitable for 35mm DIN rail
Dimensions 91.6 × 58.7 × 23.3mm

Primary Function

Convert the TTL signal into a balanced differential RS485 signal, which can be used for interface conversion and node expansion, and can also be used to extend the communication distance.
TTL TO RS485 (B) 012.jpg

Interface Introduction

TTL TO RS485 (B)101.jpg
TTL TO RS485 (B)121.png

Communication Connection Diagram

TTL convert to RS485, point to point, half-duplex communication, suitable for interface conversion

TTL TO RS485 (B)017.jpg

TTL convert to RS485, point-to-multipoint, half-duplex communication, suitable for expanding nodes

TTL TO RS485 (B)018.jpg

Two groups TTL To RS485 conversion, point-to-point, half-duplex communication, suitable for extending the communication distance of TTL

TTL TO RS485 (B)019.jpg


TTL TO RS485 01.jpg

Hardware Test

Test Note

Test Environment: PC (Windows).
Accessories required for testing:

Test Hardware Connection

The RS422 interface of TTL TO RS485 (B) is connected to the PC through the USB to RS422 conversion cable. The TTL interface of TTL TO RS485 (B) is connected with the TTL of USB TO TTL. The USB port of USB TO TTL is connected to the same PC for the self-receiving test. The schematic diagram of the hardware connection is as follows:
TTL TO RS485 02.jpg

Note: The RS485 interface of this product is also equipped with 120R Switch, the default is on, the user can set it according to the needs (set up to open, set down to NC), if signal isolation is required, you can set GND is also connected to ground.

On the PC, open two SSCOM serial port debugging assistants, open the corresponding port number, set the same baud rate, and click Send at regular intervals to send and receive normally. The screenshot of the software test is as follows:
RS232 TO RS485 (B) Spec07.jpg

Note: RS485 is a half-duplex communication, and the sending and receiving test cannot be performed at the same time.




  • Physically, the module only provides the voltage translator, no need to configure the parameters such as baud rate and node, and the Modbus communication needs to be achieved on the protocol layer.
  • Support connecting to Modbus devices (Modbus sensor, instruments, etc.), when trying to understand the Modbus protocol, you need to learn the function code and data format of Modbus. There are various function codes, and each function code has the corresponding operation; for example, reading coil status, reading input status, reading the holding register, and so on.


  • Up to 2M baud rate (stable performance).
  • The hardware solution will not limit the baud rate when using, it is mainly up to the connected TTL and RS485 devices, the communication environment and communication distance.



Technical Support

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