I got a similar case for a CJ2M-CPU31 unit, there were " 0x0200 CPU BUS UNIT ERROR 0 " from time to time. The unit would gave all 7-segment display off after power on when the Ethernet was connected. This error also found in the EIP unit error logs "0x0601 0x8000 CPU Bus Unit error". So we swapped the EIP board with another unit, the errors gone forever.