
CHAPTER 18 IEBus CONTROLLER
User’s Manual U17790EJ2V0UD
700
Table 18-18. Communication Error Source Processing List (2/2)
Overrun Error
Underrun Error/Write Error
Unit status
Reception
Transmission
Occurrence
condition
DR register cannot be read in time before the
next data is received.
DR register cannot be written in time before
the next data is transmitted.
Occurrence
condition
Location of
occurrence
Other than
data field
Data field
Other than
data field
Data field
Hardware
processing
Reception stops.
INTIE2 signal occurs.
To start bit waiting status
Remarks 1. Communication
between other units
does not end.
2. Data cannot be
received until the
overrun status is
cleared.
Transmission stops.
INTIE2 signal occurs.
To start bit waiting status
Broadcast
communication
Software
processing
DR register is read and overrun
status is cleared.
Error processing (such as
retransmission request)
Error processing (such as
retransmission request)
Hardware
processing
INTIE2 signal does not occur.
NACK signal is returned.
Data is retransmitted from
other unit.
Remark
Data cannot be
received until overrun
status is cleared.
Transmission stops.
INTIE2 signal occurs.
To start bit waiting status
Individual
communication
Software
processing
DR register is read and overrun
status is cleared.
Error processing (such as
retransmission request)
Error processing (such as
retransmission request)
Parity Error
Unit status
Reception
Transmission
Occurrence
condition
Received data and received parity do not match.
Occurrence
condition
Location of
occurrence
Other than data field
Data field
Other than
data field
Data field
Hardware
processing
Reception stops.
INTIE2 signal occurs.
To start bit waiting status
Remark
Communication between other units does not end.
Broadcast
communication
Software
processing
Error processing (such as retransmission request)
Hardware
processing
Reception stops.
INTIE2 signal occurs.
To start bit waiting status
Reception does not stop.
INTIE2 signal does not
occur.
NACK signal is returned.
Data retransmitted by other
unit is received.
Individual
communication
Software
processing
Error processing (such as
retransmission request)