Hitachi KP-FM500WCL Operation Manual page 22

(6） Transmission frame error (Master receive)
HITACHI
Slave
(KP-FM500WCL
KP-FMD500WCL)
① Session starts when ENQ is sent from master to slave.
② Slave acknowledges by returning ACK to master.
③ Master sends read command.
④ Slave returns ACK code to acknowledge read command.
⑤ Slave sends read data to master.
⑥ For some reason, master fails to receive read data.
⑦ Slave fails to receive acknowledgment of read data and attempts to resend every 3 seconds for 3
times.
⑧ After the third failure, slave aborts the sequence and ends communication.
ENQ code (05h)
ACK code (06h)
2
Read command (ASCII code)
ACK code (06h)
4
Read data (ASCII code)
5
Read data (ASCII code)
7
Read data (ASCII code)
Read data (ASCII code)
8
1
3
6
3 second
elapse
Master (Machine)
3 second
elapse
3 second
elapse
13