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Setting STM32FC0 USART1 in Modbus Communication on RS485 with DMA

Vagni
Associate III

‎2025-10-24 2:51 AM

I want to use STM32FC091 USART1 for a MODBUS communication on RS485 with DMA. The STM32FC091 USART1 has a full implementation and supports using DMA, receiver timeout interrupt, Modbus communication and driver enable features.

I just successfully tested USART1 with DMA on RS485 with my NUCLEO-C092RC. With STM32CubeMX I set USART1 in asynchronous mode and it properly works.

Test_NUCLEO-C092RC_USART1_Async.png

 But when I try to select Modbus Communication mode for USART1 I get:

Test_NUCLEO-C092RC_USART1_Modbus.png

Driver Enable (DE) for RS485 features is not available. And only a USART1_TX GPIO Setting is available, all the others are not.

How to set USART1 for Modbus Communication?

 

 

1 REPLY 1
Ghofrane GSOURI
ST Employee

‎2025-10-24 3:38 AM - edited ‎2025-10-24 5:00 AM

Hello @Vagni 

Thank you for bringing this limitation to our attention.

An internal ticket (ID: 220396) has been escalated to the development team for further investigation and resolution.

THX

Ghofrane

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