Datasheet

Section 14 IEBus™ Controller (IEB) [H8S/2258 Group]
Rev. 6.00 Mar. 18, 2010 Page 544 of 982
REJ09B0054-0600
(3) DLE Flag
When retransfer is performed up to the maximum number of transfer bytes defined by the protocol
because of reception of a NAK caused by a parity or an overrun error during data field reception,
the number of transferred bytes may be greater than that of bytes specified by the message length.
At this time the DLE flag is set. Moreover, when the value of the message length bits is greater
than the maximum number of transfer bytes, the DLE flag is also set. The DLE flag is not set if
the maximum number of transfer bytes defined by the protocol is specified and the transfer is
performed correctly.
If the DLE flag is set to 1, the RxE flag is set to 1 and the wait state is entered.
(4) PE Flag
If a parity error occurs after reception starts (the RxS flag is set to 1), a NAK is sent to perform re-
reception.
If a parity error is not cleared when the maximum number of transfer bytes specified by the
protocol is received, the PE flag is set to 1, the RxE flag is set to 1 and the wait state is entered. If
a parity error is cleared during the rereception and if the following data is received correctly, the
PE flag is not set.
Notes: 1. If the reception is performed up to the maximum number of transfer bytes defined by
the protocol because of a parity or an overrun error during data field reception, the
number of receive bytes is less than that of bytes specified by the message length bits,
no parity error or overrun error may occur at the last byte reception. In this case, the
DLE flag is set. However, the OVE and PE flags are not set.
2. The flags in IEREF are set after reception starts. Accordingly, the RxE flag is valid and
set after the RxS flag has been set. If an error occurs before reception starts, the frame
is discarded and no interrupt occurs.
14.6.6 Notes on Slave Transmission
When the slave unit transmits the slave status and upper and lower locked addresses, a parity or an
overrun error occurs in the master reception side and the data cannot be received. Accordingly,
even if a NAK is returned, the slave unit is not capable of retransfer.
In this case, the master unit must discard the frame in which an error occurred and request the
above operation in the master reception to receive the correct frame.