4.7.11 Serial Communication Reference
The serial communication reference is transferred to the frequency con-
verter as a 16-bit word. The value is transferred in whole numbers 0 -
±32767 (±200%).
16384 (4000 Hex) corresponds to 100%.
The serial communication reference has the following format: 0-16384
(4000 Hex)
≅
0-100% (Par. 204
Minimum ref.
- Par. 205
Maximum ref.
).
It is possible to change the direction of rotation via the serial reference.
This is done by converting the binary reference value to 2' complement.
See example.
Example - Control word and serial communication ref.:
The frequency converter is to receive a start command and the reference
is to be set to 50% (2000 Hex) of the reference range.
Control word = 047F Hex
⇒
Start command.
Reference = 2000 Hex
⇒
50% reference.
The frequency converter is to receive a start command and the reference
is to be set to -50% (-2000 Hex) of the reference range.
The reference value is first converted to 1' complement, and then 1 is
added binarily to obtain 2' complement:
2000 Hex
0010 0000 0000 0000 0000
1' complement
1101 1111 1111 1111 1111
+ 1
2' complement
1110 0000 0000 0000 0000
Control word = 047F Hex
⇒
Start command.
Reference = E000 Hex
⇒
-50% reference.
4.7.12 Present Output Frequency
The value of the frequency converter's present output frequency is trans-
ferred as a 16-bit word. The value is transferred as whole numbers 0 -
±32767 (±200%).
16384 (4000 Hex) corresponds to 100%.
Output frequency has the following format:
0-16384 (4000 Hex)
≅
0-100% (Par. 201
Output frequency low limit
- Par.
202
Output frequency high limit
).
Example - Status word and current output frequency:
The master receives a status message from the frequency converter that
the current output frequency is 50% of the output frequency range.
Par. 201
Output frequency low limit
= 0 Hz
Par. 202
Output frequency high limit
= 50 Hz
Status word = 0F03 Hex.
Output frequency = 2000 Hex
⇒
50% of the frequency range, corre-
sponding to 25 Hz.
4 Programming
VLT
®
Decentral FCD 300 Design Guide
108
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
4
