Danfoss VLT 6000 HVAC Series User Manual

Data control byte (BCC)
The data control byte can be explained by means of
an example: Before the first byte of the telegram is re-
ceived, the calculated check sum (BCS) is 0.
After the first byte (02H) has been received:
BCS = BCC EXOR "first byte"
(EXOR = exclusive-or gate)
BCS = 0 0 0 0 0 0 0 0 (00H)
EXOR
"first byte" =
0 0 0 0 0 0 1 0 (02H)
BCC = 0 0 0 0 0 0 1 0
Each additional, subsequent byte is gated with BCS
EXOR and results in a new BCC, such as:
BCS = 0 0 0 0 0 0 1 0 (02H)
EXOR
"second byte" =
1 1 0 1 0 1 1 0 (D6H)
BCC = 1 1 0 1 0 1 0 0
Data character (byte)
The build-up of data blocks depends on the type of
telegram. There are three types of telegram and the
telegram type applies to both control telegram (master
• slave) and reply telegram (slave • master). The three
types of telegram are the following:
1. Parameter block, used for transferring parameters
between master and slave. The data block has 12
bytes (6 words) and also contains the process
block.
2. Process block, built up as a data block with four
bytes (2 words), covering:
- Control word and reference value
(from master to slave)
- Status word and present output frequency
(from slave to master).
3. Text block, used for reading or writing texts via
the data block.
VLT
®
6000 HVAC Series
MG.61.B5.02 - VLT
®
is a registered Danfoss trademark 157
Programming

Danfoss VLT 6000 HVAC Series Specifications

General

Brand	Danfoss
Model	VLT 6000 HVAC Series
Category	DC Drives
Language	English