Contents of a character (byte)
Each transferred character begins with a start bit. Sub-
sequently, 8 data-bits are transferred, corre-sponding
to one byte. Each character is secured via a parity bit
set to "1" when there is even parity (i.e. an even num-
ber of binary 1's in the 8 data-bits and the parity bit
combined). A character ends with a stop bite and thus
consists of a total of 11 bits.
Telegram build-up under FC protocol
Each telegram begins with a start character (STX) =
02 Hex, followed by a byte that gives the telegram
length (LGE) and a byte that gives the VLT address
(ADR). Then follows a number of data bytes (variable,
depending on telegram type). The telegram ends with
a data control byte (BCC).
Telegram times
The speed of communication between a master and a
slave depends on the baud rate. The baud rate of the
frequency converter must be the same as the baud
rate of the master and is selected in parameter 502
Baudrate
.
After a reply telegram from the slave, there must be a
minimum pause of 2 characters (22 bits) before the
master is able to send another telegram. At a baudrate
of 9600 kbaud, there must be a minimum pause of 2.3
msec. After the master has completed the telegram,
the response time of the slave back to the master will
be max. 20 msec. and there will be a minimum pause
of 2 characters.
Pause time, min.:
2 characters
Response time, min.:
2 characters
Response time, max.:
20 msec.
The time between individual characters in a telegram
is not to exceed 2 characters and the telegram must
be completed within 1.5 times the rated telegram time.
If the baudrate is 9600 kbaud and the telegram length
is 16 baud, the telegram must be completed within
27.5 msec.
Telegram length (LGE)
Thetelegram length is the number of data bytes plus
address byte ADR plus data control byte BCC.
Telegrams with 4 data bytes have a length of:
LGE = 4 + 1 + 1 = 6 bytes
Telegrams with 12 data bytes have a length of:
LGE = 12 + 1 + 1 = 14 bytes
Telegrams that contain text have a length of 10+n
bytes. 10 is the fixed characters, while 'n' is variable
(depending on the length of the text).
Frequency converter address (ADR)
Two different address formats are used, in which the
address range of the frequency converter is either from
1-31 or from 1-126.
1.
Address format 1-31
The byte for this address range has the following pro-
file:
Bit 7 = 0 (address format 1-31 active)
Bit 6 is not used
Bit 5 = 1: Broadcast, address bits (0-4), not used
Bit 5 = 0: No Broadcast
Bit 0-4 = frequency converter address 1-31
2. Address format 1-126
The byte for the 1-126 address range has the following
profile:
Bit 7 = 1 (address format 1-126 active)
Bit 0-6 = frequency converter address 1-126
Bit 0-6 = 0 Broadcast
The slave sends the address byte back to the master
in the reply telegram in unchanged form.
Example:
A telegram is sent to frequency converter address 22
using address format 1-31:
VLT
®
6000 HVAC Series
156
MG.61.B5.02 - VLT
®
is a registered Danfoss trademark
Содержание VLT 6000 HVAC Series
Страница 31: ...Ordering form VLT 6000 HVAC Series MG 61 B5 02 VLT is a registered Danfoss trademark 31 Introduction to HVAC ...
Страница 63: ...Mechanical dimensions VLT 6000 HVAC Series MG 61 B5 02 VLT is a registered Danfoss trademark 63 Installation ...
Страница 75: ...VLT 6000 HVAC Series MG 61 B5 02 VLT is a registered Danfoss trademark 75 Installation ...
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