User Manual

11.7 PROFIBUS protocol
11.7.1 Telegram Format for the Profibus Protocol
For data transmission via PROFIBUS following telegram
formats are relevant for the data logger COMBILOG 1020:
Formats with fixed information section length without data
field:
S D 1 F C SD A S A F C E D
Formats with variable information section length with data
field:
SD2 LE DataUnit FCSLEr DA SA FC EDSD2
Formats with fixed information section length with data field:
SD3 DataUnit FCSDA SA FC ED
With PROFIBUS the various telegram formats are differenti-
ated by varying Start-Delimiters (SD). They can also be called
SD1-, SD2- or SD3-telegrams in this context. The telegram
formats are valid both for request and response telegrams.
However, a request telegram does not necessarily have to be
followed by a response telegram of the same format. In addi-
tion to that there is a telegram which consists of one character
only and which is used as either positive or negative acknow-
ledgement, according to the kind of request.
Short acknowledgement:
S C
Hardware Manual COMBILOG 1022
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