MODBUS - How do I wait till timeout or rx data is received?

[Sharavanth]

I am trying to implement MODBUS RTU protocol and use stm32f103c8t6 as the master.

For this, the master should send a command to the slave unit and wait till a response is received or timeout(500ms).

This version works. But, if there are other subsequent calls to poll fn, then there is a chance of data mismatch between request and response.

I cannot understand why the recursive call version does not work. The data is not being read from RX buffer in this mode.

Any help is appreciated.

PS.
To run the code, the following hardware is needed. STM32 bluepill, MAX485 TTL module and RS485 to USB converter.