Representation of the data in ProfibusDP
Deutschmann Automation GmbH & Co. KG
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UNIGATE Fieldbus Gateway CANopen® - ProfibusDP V. 2.3
26.8.11
8
Representation of the data in ProfibusDP
Any standard-compliant ProfibusDP Master can exchange data with the gateway. It is also pos-
sible to use very "simple" Master connections owing to the data structure.
8.1
Configuration telegram
After programming, the Master must send a configuration telegram to the corresponding Slave.
The configuration telegram provides the Slave with information on the length of the input/output
data. If the user has set the ’Length byte’ flag, this means the maximum data lengths. Otherwise,
it means the actual lengths.
The user normally also configures the configuration telegram in the project planning tool where
he may also, if necessary, enter the address range in which the useful data is stored.
You can write up to 16 bytes or words in one octet of the DataUnit (DU). Inputs and outputs
having the same format can be combined in one octet. Otherwise, you must use as many octets
as the number of different bytes/words you wish to use and which cannot be combined in one
octet.
If the module detects, during the check, that the maximum permitted input/output data lengths
have been exceeded, it signals incorrect configuration to the Master during a subsequent dia-
gnostic scan. It is then not ready for useful data communication.
8.2
Configuration telegram
Octet 1 0
Configuration byte 1
Octet 2 0
Configuration byte x
Structure of an octet in the configuration telegram:
Length of the data
00 = 1 byte / word
15 = 16 bytes / words
Input/output
00 = specific ID format
01 = input
10 = output
11 = input-output
0 = byte, 1 = word
0 = consistent over byte / word
1 = consistency total length