Small video about MODBUS MCU features.

• 0:00 Connections
• 1:00 Work with INPUT module
• 3:00 Configuration for OUTPUT module
• 4:00 Initial condition configuration and test
• 4.45 WATCHDOG for modbus slave configuration and test

What functionality I need from this controller? 

• Reliability!!! All Modbus slaves are connected to each other via RS485 line. If something bad happens with one device (220V on transducer for example) all other devices will die.
• My controller must be able to work with input modules(DI8, DIO4) and output modules (DO8, DIO4, RLY4, SSR4) without reprogramming MCU.
• Controller must be equipped the standard 20 pin interface for modules. 
• It will be good to have some radio interface on board.
• Radio interface configuration must be easy (w/o any additional soldering).
• The radio link is not so stable and depends on many factors, so I need some protection if the connection will be lost
• Initial condition. It will be good to have the ability to save initial outputs condition and restore it on each power on.
• Device must be as small as possible (max size 1U DIN RAIL).

I will explain the schematics etc later. Stay tuned)