如何使用 C/C++ 映射 Modbus 寄存器地址

Question

I am trying to implement a ModBus RTU Protocol over a UART Peripheral using STM32F4-Discovery Board.

I am planning to implement Master and Slave functionality using Modbus RTU.

Here are my Questions

How could i move my received data in UART to MODBUS and Transmit data from MODBUS layer to UART, using C/C++ , Please provide some code snippet that can help me understand your explanation. (As of now i am thinking of coming up with some API's please suggest some patterns)

secondly how could i implement Modbus Registers and coils. I meant how could i define there address as specified in the ModBus Application Manual. Please explain me with a code snippet. Below something i tried to implement.

/*Global Array, Structure and Variable Declarations*/
/* So to access Discrete_Output_Coils[2345] 
   the valid address to include in the protocol would be
   so we have to access address 0x929 to read the 
   data.*/
const unsigned short int Discrete_Output_Coils[4999];
const unsigned short int Discrete_Input_Contacts[4999];
const unsigned short int Analog_Input_Register[4999];
const unsigned short int Anlog_output_Holding_Register[4999];

Answer 1

I agree with user694733. You should go step by step. For example, you should define your hardware specifications (ie, what signal and of which type are they? How many? The answer to these questions will tell you how many registers and of which type will be meaningful to your "device". After that, map each signal to a register and then try to do a single register read/write operation with a CRC checking incorporated (programmed) for coils or analog. Adjust the protocol until it get what you expected, and them cover the rest of a single register type (coil, analog). Then, expand the implementation to multiple registers read/write operations. By the way, putting array declarations do not show an effort in solving the problem. You ask the community to do all the hard work. If you want some more code to start with google a little bit more. Here is a link to a library that you can study to see if it match your request: http://libmodbus.org/download/