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The application appl/goal_mb/01_simple_io demonstrates the usage of the GOAL Modbus Stack. It defines data regions for specific data types, opens up a Modbus instance and creates objects.
Footprint
The application uses with enabled logging at the platform STM32F429_nucleo about 52 kB of RAM and 240 kB of FLASH.
Data Regions
The application uses the function goal_mbCfgDataRegionDefine to define accessable regions for specific data types.
Data Type | Region |
|---|---|
GOAL_MB_DATA_COIL | 1000 to |
GOAL_MB_DATA_HOLD_REG | 3000 to |
| Note |
|---|
This function only restricts regions used by Coils and Holding Registers. Other Data Types must be handled by the application itself. |
Data Objects
The application creates objects as following:
Data Type | Name(s) | Address(es) |
|---|---|---|
Coil | APPL_COIL_1 | 1000 |
Coil | APPL_COIL_2 | 1001 |
Discrete Input | APPL_DISC_INPUT_XX1 to | 2000 -to |
Holding Register | APPL_HOLD_REG_1 | 3000 |
Holding Register | APPL_HOLD_REG_2 | 3001 |
Input Register | APPL_INPUT_REG_XX3050-30591 to | 3050 to |
Application Logic
The application provides a generic callback handler, which handles events like received read-requests or write-requests and connection-related events. Handles callback IDs are the following:
GOAL_MB_CB_ID_APPL_READYGOAL_MB_CB_ID_DATA_READthe called function
appl_readRequestProcessprovides the discrete inputs, input- and holding registers and returns random values and LED states to the requested objects.
GOAL_MB_CB_ID_DATA_WRITEthe called function
appl_writeRequestProcesshandles write requests for a holding register, setting the written value to target specific LED registers.
GOAL_MB_CB_ID_CONNECT_REQUESTGOAL_MB_CB_ID_CONNECT_RELEASEGOAL_MB_CB_ID_LED_CHANGED
Available Callback IDs are listed here.
There is also an application loop implemented, which mirrors application coils every 100 ms.