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IDL 101
COMMUNICATION
70
HB_IDL101_E_V222.doc
Gantner Instruments Test & Measurement GmbH
10.3.2. Telegram Format
For data transmission via PROFIBUS the following telegram formats are relevant for the
Datalogger IDL 101:
Formats with fixed information section length without data field:
SD1
FCS
DA
SA
FC
ED
Formats with variable information section length with data field:
SD2
LE
DataUnit
FCS
LEr
DA
SA
FC
ED
SD2
Formats with fixed information section length with data field:
SD3
DataUnit
FCS
DA
SA
FC
ED
With PROFIBUS the various telegram formats are differentiated 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 succeeded by a response telegram of the same
format. In addition to that there is a telegram which consists of only one character and which is used as either positive
or negative acknowledgement, according to the kind of request.
Short
Acknowledgement:
SC
SD
: Start-Delimiter (length = 1 byte):
The Start-Delimiter SD identifies the beginning of a telegram. It has the following values in the PROFIBUS-protocol:
telegram
format
request telegram
response telegram
data field length
SD1
hex 10
hex 10
0
SD2
hex 68
hex 68
1 ... 246 (32)
Table 10.12 Start-Delimiter (SD) in the PROFIBUS-protocol
LE
: Length (length = 1 byte):
The Length LE identifies the length of the telegram with variable data field length (SD2-telegram) and comprises the
characters from DA to DataUnit. Thus it corresponds to the length of D3 and can have values between 4 and
249.