FCM 300 / FCD 300 / VLT
®
2800 / DP V1 PROFIBUS
■ Synchronize and freeze
The control commands SYNC/UNSYNC and
FREEZE/UNFREEZE are broadcast functions.
SYNC/UNSYNC is used to send syncronized
control commands and/or speed reference to all
the connected slaves (FCM 300/FCD 300/VLT 2800
Series). FREEZE/UNFREEZE is used to freeze the
status feedback in the slaves to get syncronized
feedback fro m all connected slaves.
The synchronize and freeze commands only affect
Process Data (the PCD part of the P PO ).
SYNC/UNSYNC
SYNC/UNSYNC can be used to obtain simultaneous
reactions in several slaves, for example synchronised
start, stop or speed change . A SYNC command
will freeze the actual control word and speed
reference, incoming Process Data will be stored
but not used until a new SYNC command or a
UNSYNC command is received.
See the example below where the left column
holds the speed reference send out by the master
and the three right columns hold the actual speed
reference used in each of the three slaves.
Actual slave speed reference
VLT VLT VLT
From DP master to address: Address 3 Address 4 Address 5
1. Speed reference = 50% to address 3 50% 0% 0%
2. Speed reference = 50% to address 4 50% 50% 0%
3. Speed reference = 50% to address 5 50% 50% 50%
4. SYNC command to all addresses 50% 50% 50%
5. Speed reference = 75% to address 3 50% 50% 50%
6. Speed reference = 75% to address 4 50% 50% 50%
7. Speed reference = 75% to address 5 50% 50% 50%
8. SYNC command to all addresses 75% 75% 75%
9. Speed reference = 100% to address 3 75% 75% 75%
10. Speed reference = 50% to address 4 75% 75% 75%
11. Speed reference = 25% to address 5 75% 75% 75%
12. UNSYNC command to all addresses 100% 50% 25%
13. Speed reference = 0% to ad dress 3 0% 50% 25%
14. Speed reference = 0% to ad dress 4 0% 0% 25%
15. Speed reference = 0% to address 5 0% 0% 0%
FREEZE/UNFREEZE
FREEZE/UNFREEZE can be used to get simultaneous
reading of Process Data for example output current
from several slav
es. A FREEZE command will freeze
the current actual values and on request the slave
will send back the v alue that was present w hen
the FREEZE comm
and was received. The actual
values will be update
d when a new FREEZE or
UNFREEZE command is received.
See the example below where the left column
holds the current
values read by the m aster and
the three right columns hold the actual output
current of the three slaves.
Actual
slave output current
VLT VLT VLT
DP maste
r reads address:
Address
3
Address
4
Address
5
1. Addres
s 3 output current = 2 A
⇐ 2A 3A 4A
2. Address
4 output current = 5 A
2A ⇐ 5A 2A
3. Address 5
output current = 3 A
3A 2A ⇐ 3A
4. FREEZE com
mand to all addresses
1A 3A 3A
5. Address 3 o
utput current = 1 A
⇐ 4A 2A 5A
6. Address 4 ou
tput current = 3 A
2A ⇐ 2A 2A
7. Address 5 out
put current = 3 A
3A 1A ⇐ 2A
8. UNFREEZE comm
and to all addresses
2A 3A 4A
Reading as by 1, 2 a
nd 3
MG.90.A5.02 - VLT is a registered Danfoss trademark
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