16.3.4 Parameter data transfer
Data
communicaon with PROFINET is characterised by the simultaneous operaon of cyclic
and acyclic services in the network. As an oponal extension, the parameter data transfer
belongs to the acyclic services, which provides access to all device parameters.
Details
•
The access t
o the device data depends on the PROFIdrive prole.
•
Only one parameter request is processed at a me (no pipelining).
•
No spon
taneous messages are transferred.
•
There are only acyclic parameter requests.
Basically, a IO-Controller can always be used to request parameters from IO-Device if the IO-
Device is in the DATA_EXCHANGE state.
Transmission direcons for acyclic data transfer
Write.res
Write.req
with data (parameter request)
with data (parameter response)
without data
without data
without data
without data
Read.req
Read.res (-)
Read.req
Read.res (+)Parameter response
Parameter request Parameter request
Parameter
processing
Parameter response
IO controller
IO device
1.
A "W
rite.req" is used to transmit the data set (DB47) as parameter request to the IO-
Device.
2.
"Write.res" is used to conrm the input of the message for IO-Controller.
3.
With R
ead.req, the IO-Controller requests the response of the IO-Device
4.
The IO-Device responds with a "Read.res (-)" if processing has not been completed yet.
5.
Aer parameter processing, the parameter request is completed by transming the
par
ameter response to the IO-Controller by "Read.res (+)".
Frame structure
Destr ScrAddr VLAN Type
0x0800
RPC NDR Read/Write Block Data FCS
6 bytes 6 bytes 4 bytes 4 bytes 80 bytes 64 bytes 64 bytes 0 .... 240 bytes 4 bytes
In the "Read / Write Block eld", the iniator species the access to the "DB47" data set. The
da
ta that is wrien on this index or read by it, contain a header and the parameter request or
the parameter response. The read data or the data to be wrien are contained in the "Data"
eld.
Conguring the network
PR
OFINET
Parameter data transfer
336
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