I think that modbus can only be used with arduino using LDuino.
The only reference to modbus in the LDmicro CHANGES.txt is for version 3.4.0:
== Release 3.4.0
* Added: This release include fork
https://github.com/f1oat/LDmicro.
Compressed bytecodes, Controllino Maxi support, MODBUS support.
http://cq.cx/ladder-forum.pl?action=viewthread&parent=5007
MODBUS use RTU over TCP. But that should work also in RS485 mode by
linking with the proper Arduino library.
Announcing LDuino, an Arduino based PLC software compatible with LDmicro
http://cq.cx/ladder-forum.pl?action=viewthread&parent=5070
Controllino is here:
http://controllino.biz/
This a nice product. Unfortunately the creator got bad reputation on Kickstarter.
https://www.kickstarter.com/pr...arduino-compatible/description
More information you can get from author of Controllino Maxi support in LDmicro:
Frederic Rible <
[email protected]>
Attention! Not compatible with LDmicro2.3, if modbus contacts used.
The only reference to modbus in the LDmicro source code is for the ldinterpreter example. There is no reference to modbus in the code for the compiled version of LDmicro and no examples of how to use modbus with LDmicro on the LDmicro wiki.
The LDuino home page
https://github.com/f1oat/LDuino describes how modbus can be used with that software and has a screenshot of an example that uses modbus.