Rev. 0 / 1985-07-08
CASE Handle Error
  WHEN timeout or check sum error but no kind of retry indicated in
       temporary status register
    * request retransmission
  WHEN no (timeout or check sum error) at status request after timeout
       and no slave status error other than check sum error at transm
    indicate check sum error in temp stat reg WHEN ind in slave status
    indicate retransmission after timeout in temporary status register
    initialize output buffer pointer to top of output buffer
    set address byte identifier TB8 (SCON.3 = 1)
    move first byte from output buffer to transmit buffer
    reset serial port interrupt flags (SCON.0 and .1 = 0)
  WHEN timeout at retry and/or check sum error at retry indicated in
       temporary status register
    indicate timeout in status reg WHEN timeout or timeout at retry
    ind check sum error at transm in stat reg WHEN any check sum error
    reset temporary status register
    remove faulty unit from polling list
    indicate addressed slave not operational in status register
    set flag send CPU message
  OTHERWISE
    incr sporadic timeout error counter WHEN timeout and cntr not full
    incr sporadic check sum error counter WHEN check sum error
                                               and counter not full
    reset temporary status register
    set flag send CPU message
END Handle Error






TEMPORARY STATUS REGISTER:

+---+
! 7 ! timeout
!---!
! 6 ! timeout at retry
!---!
! 5 ! status request after timeout
!---!
! 4 ! retransmission after timeout
!---!
! 3 ! check sum error
!---!
! 2 ! check sum error at retry
!---!
! 1 ! retransmission request after check sum error
!---!
! 0 ! (spare)
+---+