Nikon NWL860 Series, Manual, Page: 17 / 96

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Chapter 3 Interface Specification
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3
● Source ID
An identification code given to the message for every source in the application level.
The source ID of a primary message is a copy of the transaction ID. When a message is
retransmitted due to errors or for other reasons, the source ID is incremented.
The source ID of a secondary message is a copy of the system byte of the received primary
message.
● Transaction ID
An integer, incremented each time a primary message is transmitted.
The same transaction ID is assigned to all blocks of a multi-block message.
4-7. Message Data
4-7-1. Format
The data in a message is written in the form of an item (item header) or list (list header).
4-7-2. Item Header Format
Item header consists of format byte (upper 6 bits) and length byte (lower 2 bits).
4-7-3. Format Byte
Format byte consists of item format code and length byte count.
4-7-4. Item Format Code
Defines the format of data.
(DATA) . . . . . . . . . . . . . . . . . . . . . . . . .
Item or
List
DATA
Item or
List
8 7 6 5 4 3 2 1
Item Format Code Length Byte Count
MSB Data Length Byte LSB
MSB Data Length Byte LSB
MSB Data Length Byte LSB
1
2
3
4
MS Byte
LS Byte
Format Byte
Length Byte
Data Format
List
Binary
Truth value
ASCII
8-byte binary integer (with sign)
2-byte binary integer (with sign)
8-byte floating point
4-byte floating point
1-byte integer (without sign)
2-byte integer (without sign)
4-byte integer (without sign)
00
10
11
20
30
32
40
44
51
52
54
octal
000000
001000
001001
010000
011000
011010
100000
100100
101001
101010
101100
bit — 876543
Format Code