Glossary
MECip
SECURE
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7
Glossary
ACK
An ACK is a positive IACK frame. If the sender detects an ACK,
then the sender´s data has been received correctly, meaning
the data has been successfully transmitted to the receiver.
Acknowledgement frames Acknowledgment on the KNX Link Layer is also called
Immediate ACK (IACK) in KNX jargon, presumably to
differentiate it from other ack methods on the upper layers.
Regarding sender and receiver, IACK frames are used to
confirm to the sender the transmitted data was received
correctly by the receiver (ACK) or not (BUSY/NACK). Also, a
receiver cannot respond by sending back an IACK when a
frame is damaged or incorrectly addressed (missing IACK).
The IACK confirmation is a mechanism within a KNX TP line or
segment. For communication across different lines or
segments, the couplers connecting the lines generate the
relevant IACKs.
BUSY
A BUSY is a negative IACK frame. If the sender detects a
BUSY, then the receiver was not able to process the received
frame. Thereafter, the sender waits for a short time period
and retries to send the frame.
Communication Object
same as Group Object
Data Point Type (DPT)
Standardized data format for transmitting values via KNX. The
complete list of DPTs is available at KNX Association.
Extended Frames format
An extended frame has a maximum APDU length of 254
octets and a maximum length of 263 octets (incl. checksum).
Filtering
Filtering of telegrams by couplers can be accomplished
according to the topology via Individual Addresses (Physical
Telegrams) and according to filter tables for group
communication via Group Addresses (Group Telegrams).
Group Address
Group addresses are used to link group communication
objects.
