Serial Interface - Block O

NOTE: Modified 03/28/05


        This is our main serial interface.  The MAX232ACWE Multichannel RS-232 Driver/Receiver contains an on board DC-DC converter to generate the voltages necessary to meet the RS-232 signal level requirements.  The extra gates and 0 ohm shunts are there so that the signal polarity can be inverted one more time.  Normally the actual RS-232 signals on the transmission line are inverted from the serial interface.  The Edelbrock serial interface is really bizarre in that it inverts everything again.  Not sure what the original purpose of the ports they chose as the serial ports.  The bizzare part is who uses an open collector inverting relay driver driven by an inverting stage as a serial port?  Maybe this is just some weird way to make a port so it is more difficult to read.  Not really sure but four inversions in each serial leg it does make for some non-standard cable arangements.   These extra gates are here to be able to either configure this port as a standard serial interface or with a double inversion which requires a special inverting cable to interface with a standard computer.