0000: signal is always
ineffective 0001: input positive
signal to SI1
0002: input positive signal to
SI2
0003: input positive signal to
SI3
0004: input positive signal to
SI4
0005: input positive signal to
SI5
0006: input positive signal to
SI6
0010: signal is always effective
0011: input negative signal to
SI1
0012: input negative signal to