New communication method user-defined extension interface (EPROT-71)

[wishinlife]

Checklist

• Checked the issue tracker for similar issues to ensure this is not a duplicate.
• Described the feature in detail and justified the reason for the request.
• Provided specific use cases and examples.

Feature description

I’m not sure whether esp-modbus has an interface that allows users to customize the implementation of other communication methods, such as Zigbee or SPI-to-UART. If the esp-modbus library has an interface, I feel that we users could implement it by writing a file similar to mbc_serial_master.c, but I haven’t looked closely at the logic inside. There are no actual hardware interface implementations for open, close, write, and read inside. It seems that to achieve what I want, I would need to implement a complete set of Modbus processing logic. Is there a way that we could just simply implement a few interfaces like open, close, write, and read and still be able to extend a new communication method?

Use cases

Zigbee gateway.

Alternatives

libmodbus.

Additional context

No response

[alisitsyn]

Hi @wishinlife ,

Thanks for the report and sorry for delays with answer. As per spec, the most useful interfaces for Modbus are RS485 (SERIAL) and TCP (UDP rare). The stack contains the transport and port layers inside, and they can be exposed. Some tests in ESP-Modbus use this approach, but it was decided to hide these layers from the user. I already have a few requests to allow users to override the public interface. However, I expect it will be hard to support because it can produce a lot of issues that are hard to reproduce without specific IO or due to incorrect implementation of IO logic.

I will consider your request to be implemented in the Modbus stack, but it will be implemented according to the priorities of other requests.