#12 I/O module drops subsequent commands

[Shigeru Kobayashi]

1. connect an I/O module to a PC
2. launch serial terminal (e.g. Acknowrich)
3. send 'KONFIGURATION_1*' to enter config 1
4. send 'h*l*'

The result should be 'h*l*', but occasionally returns
'h*!*' or 'h*'.