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11.3.4
Segmented Transfer
For data lengths > 4 Bytes the so called Segmented Transfer is used – the expedited
Transfer only supports lengths up to 4 Bytes.
In the first "Initiate" Telegram the overall amount of used data of the following se-
quence telegrams is defined.
In the following telegrams 7 data byes per telegram are send until the amount of data
bytes to be transmitted was reached. The sequences of the Segmented Transfer are
separated by a toggle bit in the command specifier for the request and the reply tele-
gram. A "Continue" Bit marks the last telegram.
11.3.4.1 Reading „Segmented Transfer"
When Reading a regular Read access via command specifier 0x40 is executed. The
response contains the command specifier 0x41 that marks the requirement of Seg-
mented Transfer for this object. The following requests alternate with command spec-
ifiers 0x60 and 0x70 until all data bytes were transmitted. In the last segment the
command specifier (bits 1...3) contains the amount of not used data bytes in that last
segment.
The resulting request and response telegrams are shown in the following sequence.
The Command Specifier have the following setup:
Initiate Upload Command Specifier:
Request:
Bit
Response:
Bit
Segment Upload Command Specifier:
Request:
Bit
Response:
Bit
Abbreviation Description
ccs
scs
n
e
s
t
c
34
7
6
5
ccs
7
6
5
scs
7
6
5
ccs
7
6
5
scs
Client command Specifier
Server command Specifier
Only valid if e =1 AND s = 1,
in all other cases n = 0.
Transfer type
Size indicator
Toggle bit, toggled with each
Segment change
Continue bit, marks following
segments
CM-CAN ACU
4
3
2
0
0
0
4
3
2
0
n
4
3
2
t
0
0
4
3
2
t
n
Values
2 = Initiate upload request
3 = Upload segment request
2 = Initiate upload response
0 = Upload segment response
If valid: Amount of data bytes, that con-
tain no useful data
0 = Normal (Segmented) Transfer
1 = Expedited Transfer (see chapter
11.3.1)
0 = Data frame size is displayed
1 = Data frame size is not displayed
0 = First and odd segments
1 = Second and even segments
0 = Further segments follow.
1 = This was the last segment.
1
0
0
0
1
0
e
s
1
0
0
0
1
0
c
04/13
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