Beckhoff KL6021-0023 Documentation page 13

The leading synchronization byte and the closing checksum are part of the EnOcean standard, and the
KL6021-0023 filters them out of the telegram, so that the displayed data starts with the telegram header
[} 13] and ends with the status field [} 13].
Longer telegrams
If the telegram from an EnOcean transmitter consists of more than 4 data bytes, it cannot be transferred in a
single K-bus cycle. In that case, the KL6021-0023 sets bit SB.1 [} 26] in the status byte in the next read
cycle, placing the next data block from the telegram into the process data.
Faulty telegrams
The KL6021-0023 calculates the checksum for every EnOcean telegram that is received. If this does not
agree with the checksum that has been transmitted the terminal sets bit SB.6 [} 26] in the status byte. A
telegram is not then placed into the data memory, and is lost.
Data memory overflow
If the telegrams received by the KL6021-0023 are not read by the higher-level controller, the terminal's
receive memory will overflow, and it will set bit SB.3 [} 26] in the status byte. It is also possible for a
telegram only to be partially written into the memory. This will automatically cause an error in the checksum,
and it will be displayed and handled accordingly.
Protocol
The following table illustrates the general structure of an EnOcean telegram:
Bit 7 Bit 0
Sync_Byte1 (0xA5)
Sync_Byte0 (0x5A)
H_Seq Length
ORG
Data Byte 3
Data Byte 2
Data Byte 1
Data Byte 0
ID Byte 3
ID Byte 2
ID Byte 1
ID Byte 0
Status
Check Sum
KL6021-0023 and KL6023
Description
Synchronization byte
Header H_Seq (3 bit)
identification
• 0 unknown transmitter ID received
• 1 known transmitter ID received
• 2 new transmitter learnt
Length (5 bit)
• Number of byte following the header
(here: 11)
Telegram type
Data byte
32 bit transmitter ID
Status field
Checksum (LSB resulting from the addition of all bytes, not
including the synchronization byte or the checksum itself)
Version: 2.0.0
Product overview
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