
CHAPTER 18 IEBus CONTROLLER
User’s Manual U17790EJ2V0UD
660
Table 18-7. Lock Setting Conditions
Broadcast Communication
Individual Communication
Control Data
Communication End
Frame End
Communication End
Frame End
3H, 6H
Note
Cannot be locked
Lock set
AH, BH
Cannot be locked
Lock set
0H, 4H, 5H, EH, FH
Cannot be locked
Note
The frame end of control data 6H (slave status read/unlock) occurs when the parity in the data field is odd,
and when the NACK signal from the IEBus unit is repeated up to the maximum number of transfer bytes
with being output.
Table 18-8. Unlock Release Conditions (While Locked)
Broadcast Communication from
Lock Request Unit
Individual Communication from
Lock Request Unit
Control Data
Communication End
Frame End
Communication End
Frame End
3H, 6H
Note
Unlocked
Remains locked
AH, BH
Unlocked
Remains locked
0H, 4H, 5H, EH, FH
Remains locked
Note
The frame end of control data 6H (slave status read/unlock) occurs when the parity in the data field is odd,
and when the NACK signal from the IEBus unit is repeated up to the maximum number of transfer bytes
with being output.
18.1.8 Bit format
The format of the bits constituting the communication frame of the IEBus is shown below.
Figure 18-9. Bit Format of IEBus
Logic “1”
Logic “0”
Preparation
period
Synchronization
period
Data period
Stop period
Preparation period:
First low-level (logic “1”) period
Synchronization period: Next high-level (logic “0”) period
Data period:
Period indicating value of bit
Stop period:
Last low-level (logic “1”) period
The synchronization period and data period are almost equal to each other in length.
The IEBus synchronizes each bit. The specifications on the time of the entire bit and the time related to the period
allocated to that bit differ depending on the type of the transmit bit, or whether the unit is the master unit or a slave
unit.
The master and slave units monitor whether each period (preparation period, synchronization period, data period,
and stop period) is output for specified time while they are in communication. If a period is not output for the specified
time, the master and slave units report a timing error, immediately terminate communication and enter the standby
status.