
CHAPTER 18 IEBus CONTROLLER
User’s Manual U16541EJ4V0UD
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(a) Timing error occurrence flag (TERR)…Bit 7
<Set/clear conditions>
Set:
This flag is set (1) if a timing error occurs.
Clear: By software
A timing error occurs if the high-/low-level width of the communication bit is not the defined value. The
defined value of the high- and low-level width is set to the bit processing block and monitored by the
internal timer. If a timing error occurs, the INTERR and INTIE2 interrupt request signals are generated.
(b) Parity error occurrence flag (PERR)…Bit 6
<Set/clear conditions>
Set:
This flag is set (1) if a parity error occurs.
Clear: By software
A parity error occurs if the parity generated in each field does not match the received parity while the
controller is serving as a receiver unit. If the parity does not match in the data field during individual
communication, however, the NACK signal is returned and retransmission of data is requested.
Therefore, the parity error does not occur.
Table 18-14. Operation if Parity Does Not Match
Field
Communication Mode
Operation if Parity Does Not Match
Master address field
Individual/broadcast
Parity error occurs.
Slave address field
Individual/broadcast
Parity error occurs.
Control data field
Individual/broadcast
Parity error occurs.
Telegraph length field
Individual/broadcast
Parity error occurs.
Individual
Retransmission is requested by returning NACK signal.
Data field
Broadcast
Parity error occurs.
(c) NACK reception error occurrence flag (NERR)…Bit 5
<Set/clear conditions>
Set:
This flag is set (1) if a NACK reception error occurs.
Clear: By software
A NACK reception error occurs if the NACK signal is received during the acknowledge bit period of the
slave address field, control data field, or telegraph length field during individual communication, regardless
of whether the controller is operating as the master or a slave. If the NACK signal is received during the
acknowledge bit period of the data field, a NACK reception error does not occur because data is
retransmitted. If the NACK signal is received during the acknowledge period of the last data field when the
maximum number of transfer bytes is reached, the NACK reception error occurs.
The NACK reception error does not occur during broadcast communication because the ACK/NACK signal
is not identified.
The NACK reception error does not occur during third-party communication because only the timing/parity
error is detected as an error.