Arm Mbed and Pelion Device Management support forum

Unable to Read Data from RS 485 Port in Two Wire Half Duplex Config of Energy Meter using MAX485 TTL Convertor

I am trying to read HOLDING REGISTERS in MODBUS protocol from an energy meter. I have used MAX RS485 to TTL convertor to connect to UART interface on STM32L476RG Nucleo-64 board. The energy meter’s COM Port blinks when the request is sent. A Digital Output Pin is connnected to DE and !RE pins to control the TX/RX on MAX 485 chip. But no response is received from it.
From what I have figured out. It seems like by the time MAX 485 chip is set in RX Mode, the energy meter has already sent the response. Please help me to overcome this issue.

If you haven’t tried yet, I would recommend capturing signals with a logic analyzer.