UIO8 and UIO20 error

[pouralise]

Hi. Currently I'm doing 3 project, with LM5, UIO20 and UIO8. But problems appear with those UIO device. When I received the device, I can download the address and application through it from ETS. And when I installed them on my customer cabinet, it works normally. But after sometime (less than 1 month to 2 month), 5/6 the device are not working. ETS can't find the UIOs address on KNX bus, I can still press the learning button of the UIOs, but in ETS, it shows no device in programing mode too. And all the Input/output of the UIOs don't working too. Each of UIOs has it's owned 24V power supply, and the KNX bus working normally. I try to use the same power supply and knx bus for the device SA42M and no problem appear like UIOs. I think the UIOs has some error that break the KNX input.
Those image below is screenshot of the LM5, UIO20 and UIO8 that I use. All the project use the same LM and UIOs as screenshot belows. Do you have any idea about what cause the problem?

1st project use 2 UIO8 and those both not working
2nd project use 2 UIO20 and 1 UIO8, and those 2 UIO20 not working, only 1 UIO 8 still working
3rd project use 1 UIO20 and 1 UIO8, and UIO 20 is not working, only UIO8 still working