Danfoss VLT HVAC Drive Metasys N2 Manual page 21

®
VLT HVAC Drive Metasys N2
2.2.4. Override/Override Release Commands and Time Out, 8-04
(Setting [20], N2 Override release)
The way the overridden points are released is very important to the way the drive will behave
during the override release time out or for release commands issued by the N2 master. This is
due to the fact that the active setup can be changed to a different setup. If one would release the
active setup before the values that have been overridden in that setup, the backup values would
then be restored to the wrong setup, leaving the overridden values in the old setup unchanged.
The release after override time out:
During an override release time-out, all points which are overridden, will be released in the order,
which they are specified in Appendix POINTMAP:
1.
2.
3.
4.
5.
2.2.5. Change of State (COS)/POLLING
A change of state occurs when a new command has been issued for the drive. This command can
be issued through the bus or through a drive related status change or command. The master can
issue a series of poll commands to the network devices to get an update on any status changes
from the time of the last polling. When polling a frequency converter for the first time after a
network has been powered up after an F command has been issued, a 0/4 poll command must
be issued.
2.2.6. Handling of Poll Message Commands
The Identity Command will cause the drive to report all AI, AO, BI and BO points, which are
available when the next Poll (0/4) is received. The drive also supports COS for AI and BI point
types. The drive is limited to responding with up to 200 ASCII characters, so multiple messages
may need to be sent before all available points have been reported.
Upon receiving the Poll (0/4), the frequency converter will begin exporting the requested infor-
mation. The frequency converter will continue to export new information upon receiving the 0/5
Poll until it has sent all requested information. Then it will respond to a new 0/5 Poll with an ACK
response to indicate all information has been transmitted and complete the Poll sequence receiving
a 0/4 Poll before sending the ACK response will cause the frequency converter to re-transmit its
latest response.
The drawing below illustrates the AI COS handling.
Release Analog Outputs from point address (NPA) 0 to 255.
Release Binary Outputs from point address (NPA) 0 to 255.
Release Internal Floating Points from point address (NPA) 0 to 255.
Release Internal Integer Points from point address (NPA) 0 to 255.
Release Internal Byte points from point address (NPA) 0 to 255.
MG.11.G1.02 - VLT ® is a registered Danfoss trademark
2. Instructions
2
21