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6. After the MMP sends the entire data file, a CRC packet is sent that contains only a packet
header (no data content).
NOTE
If required, the SC can request transmission of a particular file by sending #nnREQFIL
filename.ext (where filename.ext conforms to the 8.3 format). The MMP will send the requested
file (DOS) with the same protocol used to answer REQNEW.
7. If the SC requests a full directory listing of files on the flash card, (by sending a
#nnREQDIR command) the MMP responds by sending a listing of file names and file
sizes as described in the ‘File Transmission Protocol’ section of this document.
8. If the MMP has no data to offer it will reply with an EOD packet and wait for a
command. The MMP will terminate communications if a termination command is sent
by the surface. The SC maintains primary control of the communication. Time-out
thresholds are used as a backup. If no command is received the MMP will time out after
the third 40 second session.
9. If the SC is finished requesting data, and sends a #nnREQEOD command, the MMP
powers off the UIM and continues with the programmed deployment.
Control of Communication Session
Noise on the mooring cable could falsely trigger the Tone Detect board attached to the
SIM (however, the UIM is powered on only during the communication transaction period at the
end of a profile). The MMP/UIM pair exclusively initiate a communication session. Once the
session starts, the SC controls data transmission and the end of the communication session. The
communication session will timeout in the absence of surface controller response.
Appendix J-
5