IDL 101
COMMUNICATION
HB_IDL101_E_V222.doc
63
Gantner Instruments Test & Measurement GmbH
SD DA ReqDataUnit ED
12 n
n+4 characters
request telegram without checksum:
1
SD ResDataUnit ED
1n
n+2 characters
1
response telegram without checksum:
SD DA ReqDataUnit ED
12 n 2
n+6 characters
request telegram with checksum:
FCS
1
SD ResDataUnit ED
1n2
n+4 characters
response telegram with checksum:
FCS
1
ACK
1 character
Positive Acknowledge
NAK
1 character
Negative Acknowledge
SD
: Start-Delimiter (length = 1 byte):
The Start-Delimiter SD marks the beginning of a telegram. It has the following values in an ASCII-protocol:
SD request telegram response telegram
with check sum # >
without check sum $ =
Table 10.8 Start-Delimiter (SD) in the ASCII-protocol
DA
: Destination-Address (length = 2 byte):
The Destination-Address DA identifies the communication partner's address, to whom data shall be transmitted or from
whom data shall be requested. Destination-Address can have a value from 1 to 127 in an ASCII-protocol. The value is
here given as a two-digit ASCII-string (ASCII "01".."7F").
ReqDataUnit
: Request-Data-Unit (length = 1 ... n byte):
The Request-Data-Unit identifies a data field in the request telegram, which contains the data for the communication
partner with the DA address.
ResDataUnit
: Response-Data-Unit (length = 1 ... n byte):
The Response-Data-Unit identifies a data field in the response telegram, which contains the data for the calling
communication partner.
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