Connection timed out problem

[jacobComp]

I use libmodbus for linux and modbusino for my mcu. I realize that mcu does not respond to libmodbus request. As a consequences, libmodbus throw "Connection timed out". How can I solve it. Could you help me? My connection is checked and true. Both circuit common grounded.

[jacobComp]

Not connection wiring* :) (Busy mind)

[DamianPe]

I also have this problem when I try to address one slave just after power up and then another. Let's say my slaves are 22 adn 44. Power up, address 22, then 44. The 22 responds, the 44 not. When I change order - address the 44 after power up and then the 22 - the 44 one responds and the 22 not. Sometimes they both respond, sometimes none. Not a very stable situation...