T3-tb-8i didnt work normally

i used T3000 Controller at first time…(i didnt config or set whatever)

but it wasn’t work normally,

I inserted 12VDC to T3-TB-8I and then BEAT LED blinked

after that, Power was down to 5.5V…

pls give me some advice

Sounds like a power supply issue, could you try with a 24VAC so transformer, our T3-XX controllers take about 1VA each. Connect just the power to get started. Once it is running normally you can connect the Ethernet and/or RS485 cables for communications and once that is going you can start adding more controllers and field devices. Be sure to keep the 24vac consistent between all the devices, swapping neutral around will cause a ground loop which interrupts communications.