(3） Data transmitted by master (control abort process)
HITACHI
ENQ code (05H) 
1
2 | NACK code (15H) |
| |
| ENQ code (05H) |
| NACK code (15H) |
| ENQ code (05H) |
| Slave | NACK code (15H) | 3 |
ENQ code (05H) |
| ||
| |||
| Master (PC) | ||
|
| NACK code (15H) | |
|
|
| |
① | Master sends ENQ code to slave. |
|
|
② | Since ACK code cannot be sent, slave sent NACK code to master. |
| |
③ | Sequence is repeated 3 times in attempts to retransmit. |
| |
| After receiving the 3rd successive NACK code, communications control is aborted | ||
(4） Data transmitted by master (data error process)
ENQ code (05H)
| 1 |
2 | ACK code (06H) |
|
HITACHI
| Send data (error occurs) | 3 |
|
| |
|
| 3 second |
| Send data (error occurs) | elapse |
4 |
| |
|
|
| Slave |
|
| 3 second | |
|
|
|
| ||
| Send data (data normal) |
| elapse | ||
| 5 |
| |||
|
| Master (PC) | |||
|
|
| ACK code (06H) | ||
|
| 6 |
|
| |
|
|
|
|
| |
① | Session starts when ENQ is sent from master to slave. |
|
| ||
② | Slave acknowledges by returning ACK to master. |
|
| ||
③ | Master sends data, but slave detect error (framing, | ||||
④ | Slave detects error and does not accept data. |
|
| ||
⑤ | Sequence 3 and 4 repeats, then master transfers normal data. |
|
| ||
⑥ | Slave detects normal data and returns ACK code to master to end the session. | ||||
9