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CHAPTER 17
IEBus CONTROLLER (
PD178096A, 178098A, 178F098 ONLY)
User’s Manual U12790EJ2V0UD
(d) Slave transmission enable flag (ENSLVTX)...Bit 4
<Set/reset conditions>
Set:
By software
Reset: By software
Cautions 1. Clear the ENSLVTX flag before setting the MSTRQ flag when making a master request.
If a slave transmission request is sent in slave mode when the ENSLVTX flag is unset,
NACK in the control field will be returned. Moreover, when returning to an enabled state
from a disabled state, transmission becomes valid from the next frame.
2. If the controller receives control data for data/control writing (3H, 7H) when the
ENSLVTX flag is unset, NACK will be returned via the acknowledge bit of the control
field.
3. The ENSLVTX flag will be set and the status interrupt (INTIE2) will be generated when
the control data (0H, 4H, 5H, 6H) of a slave status request is returned, even if the
ENSLVTX flag is in the reset status. At this time, the data returned via the acknowledge
bit of the control field (ACK or NACK) depends on the status of the local unit and the
received control data.
(e) Slave reception enable flag (ENSLVRX)...Bit 3
<Set/reset conditions>
Set:
By software
Reset: By software
Caution If the ENSLVRX flag is reset when the IEBus is busy with other CPU processing, NACK will
be returned via the acknowledge bit of the control field, making it possible to disable slave
reception.
Note that resetting this flag only disables individual communication, not
broadcast communication. If the received slave address matches the unit address during
individual communication, however, the start interrupt (INTIE2) is generated.
If CPU
processing has priority (neither reception nor transmission occurs), be sure to stop the
IEBus unit by resetting the ENIEBUS flag. Note also that when returning to an enabled state
from a disabled state, transmission becomes valid from the next frame.