Shenzhen
3onedata Technology Co., Ltd
21
www.3onedata.com
Make reference to the segment transfer protocol message segment in DeviceNet. Segmented message format are
shown in (to extend the frame as an example, standard frame is just a different length of the frame ID, other the
same format), transmission of Modbus protocol can from "data 2" start byte, if the file is greater than 7 bytes, then
the rest of the file within the volume according to the paragraphing continue the conversion until completion of the
conversion.
Table 6.3.1.1 CAN2.0 Extended Frame Format
7
6
5
4
3
2
1
0
Frame information
FF
RTR
x
x
DLC
(
data length
)
Frame ID1
x
x
x
ID.28—ID.24
Frame ID2
ID.23—ID.16
Frame ID3
ID.15—ID.8
Frame ID4
ID.7—ID.0
Data 1
Segment Mark
Segment Counter
Data 2
Character 1
Data 3
Character 2
Data 4
Character 3
Data 5
Character 4
Data 6
Character 5
Data 7
Character 6
Data 8
Character 7
Segment Mark:
The message is segmented message or a separate message. If the value of 0 is a separate message,
a value of 1 is a message in Segment.
Segment type:
indicate that the packet is not segmented, the first segment, the middle segment, or the last segment.
Table 6.3.1.2 Segment type position
Position
Type
Describe
00
No segment
That message does not segment
01
The first segment
If the segment counter has a value of 0, so
this is the first stage in the series
10
The middle segment That this is an intermediate segment
11
The last segment
Mark the last segment
Segment Counter:
Mark each segment, the segment in the message number, if it is a 'N' segment, then counter value
is
‘
N
’
. So at the receiver can verify whether the segment is lost, so the sectional counting ranges: 1-63 (bit 0~5).