I agree with PLCMentor. I've found it can be a pain to troubleshoot. You really have to stick to the rules that A-B lays out for DeviceNet.
We once had an outside contractor install some equipment and he didn't use a dedicate power supply. The power supply was also being used to feed PLC inputs...
Here's how I do it...
button Bit1 Bit2
001 ---][--------]/[----------( )--
button Bit1
002 ---][---------------------( )--
Bit2 Out Bit3
003 ---][-----+-----]/[-------(L)--
|
| Out Bit3...