ESP-Modbus Library

An Espressif ESP-Modbus Library (esp-modbus) is a library to support Modbus communication in the networks based on RS485 or Ethernet interfaces. The Modbus is a data communications protocol originally published by Modicon (now Schneider Electric) in 1979 for use with its programmable logic controllers (PLCs).

• The Overview, Messaging Model And Data Mapping
• Modbus Port Initialization
• Master Communication Options
• Slave Communication Options
• Modbus Master API
• Modbus Slave API
• Possible Communication Issues And Solutions
• Application Example
• Protocol References
• API Reference
• Modbus Endianness Conversion API Reference

Note

The ESP-Modbus library starting from version v2.0.0 supports creation of several instances of Modbus master and slave objects. The instance of each type shall be created using appropriate constructor API which uses the pointer to predefined object configuration options as first parameter and returns the pointer to created communication object as a second parameter. The returned pointer shall be saved and later be used as instance identifier in first parameter of each call of Modbus API functions.