The client wants to develop a converter module that allows the TTL interface of the microcontroller to be transferred to the RS485 module (MODBUS).

• ESP32 Wroom
• RS-485 transceiver
• Multivibrator
• Digital isolator
• DB-9 RS232 to TTL Converter
• MAX-485 TTL to RS-485 Converter Module
• Male jumper wires
• Casing (Breadboard for testing)

In this project, we have designed a circuit to convert RS232 signals to RS485 Signals. We have designed this circuit to increase the transmission range up to 1000 feet. As we know that the normal transmission range of the RS-232 port is less than 50 feet which put a limit to its usage in industrial applications. To enhance its range we have created an RS232 to RS485 converter circuit after which the range will be exceeded by 1000 feet.

1. 01

   Collecting the prerequisites:

   For this, first, we collected all prerequisites mentioned above and arrange for power supply voltage.

2. 02

   Design the circuit:

   We used a schematic editor to design the circuit based on the selected components and the requirements. The circuit should include a motor driver, microcontroller, weigh module, PLC, and level shifters. Level shifters are used to convert the RS232 voltage levels to the RS485 voltage levels, and vice versa.

3. 03

   Simulate and fabricate the circuit:

   We use a circuit simulator to simulate the circuit and create a physical circuit board according to the schematic designed by our experts.

4. 04

   Test and optimize the circuit:

   Our dedicated developers use a multimeter and an oscilloscope to test the circuit. Also, we optimized the circuit to improve its performance.

• Firmware Language: C
• Development Chip: ESP32
• Communication Protocol: RS232 , MAX 232 , RS 485 , MODBUS

We have provided a solution that uses a microcontroller bridge to convert the RS-232 to the RS485 (MODBUS) signal.

• The controller takes the RS232 signal as an input buffer and makes a packet to send to the slave device.
• This solution works as a bridge between PLCs and RS485 slave devices.
• Working Process: The ESP32 has two UART communication ports.
• On one port, we connect the DB-9 RS2stud32 converter and receive data.
• On the second UART port, we connect the MAX-485 TTL to the RS485 Converter module to send and receive data.