
CHAPTER 18 IEBus CONTROLLER
User’s Manual U16541EJ4V0UD
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(b) Last acknowledge bit of control field
The last acknowledge bit of the control field serves as a NACK signal in any of the following cases, and
transmission is stopped.
If the parity of the control bit is incorrect
If control bit 3 is ‘1’ (write operation) when the slave reception enable flag (BCR.ENSLVRX bit) is not set
(1)
Note
If the control bit indicates reading of data (3H or 7H) when the slave transmission enable flag
(BCR.ENSLVTX bit) is not set (1)
Note
If a unit other than that has set locking requests 3H, 6H, 7H, AH, BH, EH, or FH of the control bit when
locking is set
If the control bit indicates reading of lock addresses (4H, 5H) even when locking is not set
If a timing error occurs
If the control bit is undefined
Note
See 18.3 (1) IEBus control register (BCR).
Cautions 1. The ACK signal is always returned when the control data of the slave status request
is received, even if the ENSLVTX bit = 0.
2. The NACK signal is returned by the acknowledge bit in the control field when the
control data for data/command writing is received, even if the ENSLVRX bit = 0.
Slave reception can be disabled (communication stopped) by ENSLVRX bit only in
the case of individual communication.
In the case of broadcast communication,
communication is maintained and the data request interrupt request signal (INTIE1)
or IEBus end interrupt request signal (INTIE2) is generated.
(c) Last acknowledge bit of telegraph length field
The last acknowledge bit of the telegraph length field serves as a NACK signal in any of the following
cases, and transmission is stopped.
If the parity of the telegraph length bit is incorrect
If a timing error occurs
(d) Last acknowledge bit of data field
The last acknowledge bit of the data field serves as a NACK signal in any of the following cases, and
transmission is stopped.
If the parity of the data bit is incorrectNote
If a timing error occurs after the preceding acknowledge bit has been transmitted
If the receive data is stored in the DR register and no more data can be receivedNote
Note
In this case, when the communication executed is individual communication, if the maximum
number of transmit bytes is within the value that can be transmitted in one frame, the
transmission side executes transmission of that data field again. For broadcast communication,
the transmission side does not execute transmission again, a communication error occurs on the
reception side and reception stops.