The DIO-64 provides 32 digital input channels , 32 output channels and 6 counter/timer channels The DIO-64 consists of two 16-bit input port and two 16-bit output port . The user can use the DB-16P ( or 782 series ) to. Connect the input port (CN2,CN4) for isolation purpose. The user can use DB-16R (or 785 series) to interface to the output port (CN1,CN3) for relay control. There are four clock source , 2 M , 1 M , 500 k , 250 k, on the board . The user can choose any one by jumper setting .The user can take the frequency from the soldering pad. On board Timer/Counter provides 3-channel for frequency measure , event counting and pulse generation. The optional 8254 provides 3-channel for interrupt use.