Danfoss VLT HVAC Drive FC 102 Design Manual page 230

Appendix
A number of data bytes (variable, depending on the type
of telegram) follows.
A data control byte (BCC) completes the telegram.
STX LGE
Illustration 14.6 Telegram Structure
14.5.3 Telegram Length (LGE)
The telegram length is the number of data bytes plus the
address byte ADR and the data control byte BCC.
•
The length of telegrams with 4 data bytes is
LGE=4+1+1=6 bytes.
•
The length of telegrams with 12 data bytes is
LGE=12+1+1=14 bytes.
•
The length of telegrams containing texts is 10
bytes.
1) The 10 represents the fixed characters, while the n is
variable (depending on the length of the text).
14 14
228
VLT
ADR DATA
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®
HVAC Drive FC 102
14.5.4 Drive Address (ADR)
Two different address formats are used.
The address range of the drive is either 1–31 or 1–126.
•
Address format 1–31
BCC
•
Address format 1–126
The slave returns the address byte unchanged to the
master in the response telegram.
1) +n
14.5.5 Data Control Byte (BCC)
The checksum is calculated as an XOR-function. Before the
first byte in the telegram is received, the calculated
checksum is 0.
- Bit 7=0 (address format 1–31 active).
-
Bit 6 is not used.
- Bit 5=1: Broadcast, address bits (0–4) are
not used.
- Bit 5=0: No broadcast.
-
Bit 0–4=drive address 1–31.
- Bit 7=1 (address format 1–126 active).
-
Bit 0–6=drive address 1–126.
- Bit 0–6=0 broadcast.
MG16C302