APPENDIX. HOST COMMUNICATION PROTOCOL
IMR02E20-E1
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(6) ACK (Acknowledgment)
An acknowledgment ACK is sent by the host computer when data received is correct. When the SRZ
unit receives ACK from the host computer, the SRZ unit will send any remaining data of the next
identifier without additional action from the host computer. When host computer determines to
terminate the data link, EOT is sent from the host computer.
When ACK is received after ETX and BCC are sent, the next identifier data is sent according to the
order of the communication data list.
When ACK is received after ETB and BCC are sent, the data after ETB is sent.
(7) NAK (Negative acknowledge)
If the host computer does not receive correct data from the SRZ unit, it sends a negative
acknowledgment NAK to the SRZ unit. The SRZ unit will re-send the same data when NAK is
received. This cycle will go on continuously until either recovery is achieved or the data link is
corrected at the host computer.
The format of the data that an SRZ unit re-sends is as follows.
(8) No response from host computer
When the host computer does not respond within approximately three seconds after the SRZ unit
sends data, the SRZ unit sends EOT to terminate the data link (time-out time: about 3 seconds).
(9) Indefinite response from host computer
The SRZ unit sends EOT to terminate the data link when the host computer response is indefinite.
(10) EOT (Data link termination)
The host computer sends EOT message when it is necessary to suspend communication with the SRZ
unit or to terminate the data link due lack of response from the SRZ unit.
Identifier Data
BCC
ETB
or
ETX
STX
