Response shifted in ucMasterRTURcvBuf

[oussemagaied]

the problem is triggered following these steps:
1.1 - Plug the USB RS485 interface and run a modbus server script in PC side (uModbus "python")
1.2 - Request reading coils every 3 seconds (Freemodbus running on Atmel SAMDJ17A)
1.3 - Close the script and re-open it on the first read retry after the timeout

So what actually happens here :
Script response is shifted on the ucMasterRTURcvBuf buffer so the response is always incorrect thus read coil timeout
yet the response is not shifted on the USART circular fifo buffer.