5.5 Data Structure in the Acyclic Telegrams
The data structure for a write/read parameter request
consists of 3 main blocks:
•
Header block.
•
Parameter block.
•
Data block.
Arrange according to
:
Word number
1 Header
Request #
Request ID
2 Header
Axis
# Param.
3 (Param. 1)
Attribute
# Elements
4 (Param. 1)
Parameter number
5 (Param. 1)
Subindex number
6 (Param. 2)
Attribute
# Elements
7 (Param. 2)
Parameter number
8 (Param. 2)
Subindex number
9 (Param. 3)
Attribute
# Elements
10 (Param. 3)
Parameter number
11 (Param. 3)
Subindex number
...
N (Data Param. 1)
Format
# Elements
N+1 (Data Param. 1)
Data
Data
N (Data Param. 2)
Format
# Elements
N+1 (Data Param. 2)
Data
Data
N (Data Param. 3)
Format
# Elements
N+1 (Data Param. 3)
Data
Data
N+1 (Data Param. 3)
Data
Data
N+1 (Data Param. 3)
Data
Data
Table 5.1 Request Telegram
5.6 Header
Request number
The master uses request # to handle the response from the
IO device. The IO device mirrors this number in its
response.
Request ID
1 = request parameter
2 = change parameter
Axis
Always leave this to 0 (zero).
Only used in multi-axis system.
Number of parameters
Number of parameters to read or write.
5.7 Parameter Block
Provide the following 5 values for each parameter to read.
Attribute
Attribute to be read
10 = Value
20 = Description
30 = Text
Number of elements
The number of elements to read when parameter is
indexed.
Attribute
Read attribute.
Parameter number
The number of the parameter to read.
Subindex
Pointer to the index.
5.8 Data Block
The data block is only needed for write commands. Set up
the data block information for each parameter to write.
Format
The format of the information to write:
2: Integer 8.
3: Integer 16.
4: Integer 32.
5: Unsigned 8.
6: Unsigned 16.
7: Unsigned 32.
9: Visible string.
33: Normalized value 2 bytes.
35: Bit sequence of 16 boolean variables.
54: Time difference without date.
Refer to the frequency converter’s
programming guide
for a
table with parameter number, format, and other relevant
information.
Data
The actual value to transfer. The amount of data has to be
exactly the size requested in the parameter block. If the
size differs, the request generates an error.
On a successful transmission of a request command, the
master can read the response from the frequency
converter. The response does look very much like the
request command. The response only consists of 2 blocks,
the header and the data block.
Acyclic Communication (DP-V...
PROFINET
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