Hitachi Kokusai Electric KP-F500PCL Operation Manual page 18

(1) Transmission from master (normal process)
HITACHI
Slave
(KP-F500PCL/SCL
KP-FR500PCL/SCL)
① Session starts when ENQ is sent from master to slave.
② Slave acknowledges by returning ACK to master.
③ Master sends data to slave.
④ Slave acknowledges receipt of data by again returning ACK to master and end the handshake.
(2） Master reads data (normal process)
HITACHI
Slave
(KP-F500PCL/SCL
KP-FR500PCL/SCL)
① Session starts when ENQ is sent from master to slave.
② Slave acknowledges by returning ACK to master.
③ Master sends read command to slave.
④ Slave receives read command, then acknowledges by returning ACK code to master.
⑤ Slave sends read data to master.
⑥ Master receives read data, then acknowledges by returning ACK code to slave.
ENQ code (05H）
ACK code (06H)
2
Transmit data (ASCII code)
ACK code (06H)
4
ENQ code (05H)
ACK code (06H)
2
Read command (ASCII code)
ACK code (06H)
4
Read data (ASCII code)
5
ACK code (06H)
1
3
Master (PC)
1
3
Master (PC)
6
8