The logic I/Os are managed by program on process image, so they are not directly accessible by modbus commands. The modbus commands can act only on the DB100 data memory. The DB100 area is accessible by all the modbus commads at offset address 40000.
If you need to manage the logic I/Os by modbus you must write a simple program that copies the logic inputs to a BOOL variables on DB100 and copies BOOL variables from DB100 to logic outputs. This program can be writen by using any language, here the ModbusIOs program download, it’s a simple project with two example programs, one in LD ladder diagram and one in ST structured text (Screenshot).
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