Urgent !! STM32F4 COMMUNICATION PROBLEM SIEMENS PLC WITH RS485 EXAMPLE

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I want to connect with rs485 to ttl converter for commucinate with SIEMENS PLC but I cannot write start read adress in stm32f4(I use mikroc pro for arm)

In my stm32f4 I read information with UART and I use rs485 to ttl converter for PLC commucination

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like that picture example

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I want to use stm32f411 instead of the arduino

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I want to use stm32f411 instead of the arduino