


                                6500 Test Functions              
                                                                10/19/92 



        The 6500 has two levels of built in RS232 diagnostics.  The first 
        level is run every time the instrument is powered up.  This level 
        does a check of the UART, and displays the message:

                                RS232: AVAILABLE

        on the third line of the crt if all goes well.  If the UART is 
        found not to be OK the message:

                                RS232: BAD UART

        will be displayed. If you get the "BAD UART" message you should 
        contact Frye Electronics as you probably have defective hardware.


        The second diagnostic is run if the loop-back plug (furnished 
        with the RS232 option) is plugged into the back of the 
        instrument.  This test checks the UART more completely, checks 
        the RS232 driver chips, the cable from the rear panel DB25 
        connector to the I/O board, and the RS232 interrupt.  This 
        diagnostic test displays:

                                RS232: DIAGNOSTICS PASSED

        if all goes well.  It will display:

                                RS232: NO INTERRUPT

        if the interrupt jumper is missing, incorrectly plugged in, or if 
        the trace on the back of the board is not cut.  It displays:

                                RS232: BAD CABLE

        if the cable from the I/O board to the rear panel is plugged in 
        backward. 

        If level two diagnostics are run, it is recommended that the 
        machine be turned off, the loop-back plug removed, then 
        operations restarted as the serial port may not be correctly 
        initialized.








        -med
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