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Modbus RTU problem with de signal

Posted: Sat May 25, 2024 8:54 am
by luk_ab
I'm using the modbus master example, since I'm having problems with the communication of my device I examined the signals on the TX RX and DE pins. Below you can see that the EN signal goes low before TX finishes transmitting.
Logic_KFOZGr5i7a.png
logic
Logic_KFOZGr5i7a.png (105.27 KiB) Viewed 1706 times
How can I fix this? Modbus speed 9600 TX - GPIO23 RX - GPIO22 DE - GPIO18

Re: Modbus RTU problem with de signal

Posted: Mon May 27, 2024 9:14 am
by ESP_alisitsyn
Hi @luk_ab,

Which version of esp-idf you are using? The issue you describe looks as already resolved issue with the UART driver in RS485 mode.

Re: Modbus RTU problem with de signal

Posted: Mon May 27, 2024 5:14 pm
by luk_ab
Hi @ESP_alisytsyn in this project I am using ESP-IDF v5.1.2 communication I run on UART 2. I momentarily coped by using a separate task to control the DE pin. From which version of IDF does this work correctly?

Re: Modbus RTU problem with de signal

Posted: Fri Jul 19, 2024 8:10 am
by ESP_alisitsyn
Hi @luk_ab,

Sorry for the late response.
As per my information the issue is fixed by commit https://github.com/espressif/esp-idf/co ... 9338ccdf37