Danfoss VLT Brook Crompton Motor FCM 300, Design Manual

Page: 65 / 102

Illustration 3.35
The parameter value depends on the command given. If
the master wants a parameter (read), it does not care
about the PWE block value. If a parameter is changed by
the master (write), the new value is transferred in the PWE
block. If the slave replies to a parameter request (read
command), the present parameter value is transferred to
the PWE block.
The transferred value corresponds to the figures given in
the parameter description. E.g. parameter 101, where [1]
corresponds to
Constant torque , [2] corresponds to Variable
torque: low , etc. However, parameters with data type 9
(text string) are excepted, as this text is transferred as an
ASCII text string. When a text string is transferred (read),
the telegram length is variable, since the texts have
different lengths. The telegram length is stated in the 2nd
byte of the telegram, called LGE, see
3.6.3 Telegram Build-
up . Parameters 621-634 (nameplate data) have data type 9
(text string).
Data Types Supported by the VLT Frequency Converter
Data type Description
3 Integer 16
4 Integer 32
5 Unsigned 8
6 Unsigned 16
7 Unsigned 32
9 Text string
Table 3.21
Unsigned means there is no sign included in the telegram.
The different attributes for each parameter can be seen in
the section on factory settings. Since a parameter value
can only be transferred as an integer, a conversion factor
must be used to transfer decimals.
Example:
Parameter 201: minimum frequency, conversion factor 0,1.
If parameter 201 is to be set to 10 Hz, a value of 100 must
be transferred, since a conversion factor of 0,1 means that
the transferred value will be multiplied by 0.1. A value of
100 will thus be understood as 10.
Addressing by unit ID
The unit ID is printed on the label on the plastic cover
under the lid of the electronics box. The three groups of
unit ID each with three digits must be converted to Hex.
The desired address is added as the last byte. The frame is
sent to the bus address parameter(s) 500 (and 918) via a
broadcast.
PKE: Write to parameter No. 500 or 918
IND: Not Used
2. Process-bytes
The process byte block is divided into two blocks each of
16 bits, which always come in the sequence stated.
Illustration 3.36
PCD1 PCD2
Control telegram
(master
⇒
slave)
Control word Reference value
Reply telegram
(slave
⇒
master)
Status word Given output
frequency
Table 3.22
3.6.5 Control Word According to Fieldbus
Profile Standard
(parameter 512 = Fieldbus Profile) The control word is
used for transmitting commands from a master (e.g. a PC)
to a slave (FC motor).
Programming
VLT
®
DriveMotor FCM Series
MG03BA02 - VLT
®
is a registered Danfoss trademark 63
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