Instruction manual

ACU-1000 Operations Manual
Interoperability Now 5-7
The /PTT, /AuxO1, and /AuxO2 digital outputs are generated by transistors Q11, Q12, and Q13
which are driven by the CPU IC, U4. Digital inputs /COR, /AuxI1, and /AuxI2 are routed to
input gates on CPU, U4.
An RS-232 interface chip, U27, changes RS-232 voltage levels into TTL voltage levels for
processing by the DSP module.
Similarly, an Ethernet transceiver chip, U6 provides the network interface logic between the
RJ-45 network connector and the CPU, U4.