VLT
®
Series 3500
86
Byte 5 through 8:
Control and status words, used to send commands to the
frequency converter and to send status from the frequency
converter to the master.
Byte 9 through 12:
The parameter number is inserted in these bytes.
Byte 13:
Used for the sign before data value in bytes 14 through 18.
All characters other than “-” are taken as “+”.
Byte 14 through 18:
Here is placed the data value of the parameter stated in
bytes 9 through 12. The value must be a whole number. If a
decimal point is needed, it is stated in byte 19.
NOTE:
Some data values have brackets with a number, for
example “[0]”. Use this number instead of the “Text”
data value.
Byte 19:
The position of the decimal point in the data value stated in
bytes 14-18. The number states the number of characters
after the decimal point. Consequently, byte 19 can be 0, 1,
2, 3, 4 or 5. For example, the number 23.75 is stated:
Byte no. 13 14 15 16 17 18 19
in ASCII character + 23750 3
If byte 19 = 9, this indicates an unknown parameter.
Byte 20 and 21:
Used for check sum control from bytes 2 up to and includ-
ing 19. The decimal values of the ASCII characters are
added and reduced to the two low characters, for example:
Σ 235 - reduced = 35. If there is to be no control, the func-
tion can be cancelled by means of the “?” character (ASCII:
63) in the two bytes.
Byte 22:
Stop byte, stating the end of the telegram. The character
“>” is used (ASCII: 62).
Byte 1:
Start byte, which in this case must be the character "<"
(ASCII: 60).
Byte 2 and 3:
The two-digit address of the frequency converter. This ad-
dress is also programmed in parameter 500. Sending to ad-
dress 00 means transmission to all units connected to the
bus. None of the units will reply, but they will carry out the
command.
Byte 4:
Control parameter telling the drive what to do with the fol-
lowing data values.
U (update)
Means that the data value, bytes 13 through 19, must be
read into the drive parameter specified by bytes 9 through
12.
R (read)
Means that the master wishes to read the data value of the
parameter in bytes 9 through 12.
C (control)
Means that the frequency converter reads only the four
command bytes, 5 through 8, and returns with status. Para-
meter number and data value are ignored.
I (read index)
Means that the frequency converter reads the index and
parameter and returns with status. The parameter is stated
in bytes 9 through 12 and index is stated in bytes 13
through 18.
Parameters with indices are read-only parameters. Action
will be taken on the control word. Two-dimensional indices
(x,y) (parameters 601 and 602) are separated by a comma,
see byte 19.
Example:
Index = x, y
Data value = 013.05
Byte 14 through 18 = 01305
Byte 19 = 2
=
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