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CHAPTER 17
IEBus CONTROLLER (
PD178096A, 178098A, 178F098 ONLY)
User’s Manual U12790EJ2V0UD
(c) Acknowledge bit at end of telegraph length field
The acknowledge bit at the end of the telegraph length field serves as NACK 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) Acknowledge bit at end of data field
The acknowledge bit at the end of the data field serves as NACK 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 receive data is stored in the IEBus data register (DR) 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.
17.1.7 Transfer data
(1) Slave status
The master unit can learn why the slave unit did not return the acknowledge bit (ACK) by reading the slave status.
The slave status is determined according to the result of the last communication the slave unit has executed.
All the slave units can supply information on the slave status.
The configuration of the slave status is shown below.