WEG DeviceNet CFW500 User Manual - page 26
2. When receiving the telegram, the CFW500 will test the data consistency in order to know if the request is
valid. If errors in the request format are not found, it will respond positively to the request telegram and
initiate the data treatment.
3. After receiving writing telegram positive response, reading DP-V1 telegrams (DS_Read) must be sent in
order to obtain the response to the request performed previously. If the request has not been processed
yet, the drive will respond a reading error. This reading must be repeated until the drive responds with valid
data.
The fields with the request and response data contain the structure where the parameters accessed at the drive
are defined. In this access, as defined by the PROFIdrive, the request and response data have the following
structure:
Table 5.1: Request data structure
Request data header
Request Reference
Request ID
DO-ID
Nr. of Parameters (n)
Parameter address
Attribute
Nr. of Elements
Repeated 'n' times, according
to the number of accessed
parameters
Parameter Number
Sub-index
...
Parameter value (only for
parameter modification requests)
Format
Number of Values
Repeated 'n' times, according
to the number of parameters
in the header
Value 1
Value 2...
...
Request Reference
A number between 1 and 255 that will be retransmitted in the response telegram.
Request ID
It represents the type of request made to the slave:
1 = Parameter reading
2 = Parameter modification
DO-ID
0
Nr. of Parameters
The number of parameters accessed in the request.
Attribute
10h (request of the parameter value)
Nr. of Elements
For parameters of the array type, it represents the number of elements accessed in the parameter. For
the CFW500 only a few parameters specified by the PROFIdrive specification have this format, the other
parameters are always formed by a single value, and therefore this field must be set in 0 or 1.
Parameter Number
The number of a drive valid parameter (the most significant byte is transmitted first).
Sub-index
For parameters of the array type, it represents the array element starting from which the access will be
made (the most significant byte is transmitted first). For parameters formed by a single item, this field
must be set in 0.
Format
It defines the format for the writing parameter. For the CFW500 parameters the value 42h (16 bit word)
must be used.
Number of Values
The number of values to be written (defined in the number of elements).
Value
Value to write in the parameter (the most significant byte is transmitted first).
Table 5.2: Response data structure
Response data header
Request Reference mirror
Response ID
DO-ID mirror
No. of Parameters (n)
Parameter value (only for
parameter reading responses, or in
case of error)
Format
Number of Values
Repeated 'n' times, according
to the number of accessed
parameters
Value 1 or error code
Value 2 or error code...
...
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