Copyright (c) 1997 Ken Hancock <kenh@vgi.com>
This document resides at http://members.aol.com/khancock/nbuddy/

This document is coprighted.  The document and information contained
herein may be used freely, however do not distribute modified copies of
this document.  If you intend on mirroring this document on another web
site, please mail me so I can advise you of updates.

If you have updates to this documentation, please mail them to
kenh@vgi.com so that the master document can be updated and distributed
to any mirror sites.

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The following serial packets are used with communicating with the N90s:

NIKON Unit Inquiry/1200 baud

QUERY:      $53 31 30 30 30 05
RESPONSE:   $31 30 32 30 46 39 30 58      1020F90X
            $2F 4E 39 30 53 00 03 06      /N90S...
         
         
N90S Command Packet - 9 bytes

  02   |  20   |  80   |  02   |  02   |  02   |  FD   |  00   |  03   |
 start | cflag | mode  |        address        |    length     | stop  |
1 byte |1 byte |1 byte |        3 bytes        |    2 bytes    |1 byte |


N90S Data Packet - 3+length bytes

  02   |     data      |   00  |   03  |        chk = SUM(data)
 start |               |  chk  |  stop |
1 byte |    n bytes    |1 byte |1 byte |


N90S Status Packet

  06   |   00  |
     status    |
     2 bytes   |

0x0600 = OK

N90S Signoff Packet - resets the camera to default (1200) baud
                      This packet is echoed by the camera

  04   |   04  |
    signoff    |
    2 bytes    |

Command Packets:

mode
----

80 read data
81 write data  - Command packet WITHOUT STOP BYTE followed by a data packet
85 shutter release - address/length = 0
86 focus camera - address/length = 0
87 change baud   - address = 0x050000 for 9600 baud; length = 0
1B memo holder info - address = 0x920000; length = 0

Communication between the N90S and the host is comprises a number of
sessions.  A session begins with a NIKON UNIT INQUIRY, a series of
command and data packets in quick succession, folled by a Signoff
Packet.  example: read in a list of settings, show them on the host, and
then change individual settings would be broken up into a single session
for reading all options, and then possibly multiple sessions for
changing individual settings.

See the examples document for some examples of a session.