37
MG.60.N1.22
- VLT is a registered Danfoss trademark
VLT
®
5000 / VLT
®
6000
HVAC / VLT
®
8000 AQUA
Standard
Object
Support
The VLT LonWorks option supports two
standard objects and three SNVTs, per the
LonMark standard object philosophy. The
standard objects are the
Node Object
(containing the
Object request, Object status,
and
Object alarm)
and the
Controller object
,
(containing the network variables described
in the preceding sections). The
Object request
is a LonMark device used to obtain status and
alarm information from a node.
It is not necessary for a controller to support
the
Node Object
network variables. The
Object request, Object status
and
Object
alarm
provide status and alarm information
for controllers that only support this type of
functionality. The status and alarm functions
described in the preceding sections contain
more drive specific information than
Object
status
and
Object alarm.
1. The VLT sends an
Object status
containing drive status information
and an
Object alarm
containing fault
informationin response to the
following
Object requests
:
RQ_NORMAL,
RQ_UPDATE_STATUS, and
RQ_UPDATE_ALARM.
Network Variables for Node Object Support
Function
SNVT type
Variable Name
Input/Output
Object request
SNVT_obj_request
nviRequest
Input
Object status
SNVT_obj_status
nvoStatus
Output
Object alarm
SNVT_alarm
nvoAlarm
Output
A controller node error is written to VLT
parameter 201,
Output Frequency Low Limit,
with 80.0 Hz when the high limit is 60 Hz
.
The
conversion index is -1, with conversion factor 0.1.
The controller node sends the following
parameter write request to the VLT.
nvoParamCmd.learn =
LN_LEARN_CURRENT
nvoParamCmd.selector = 201
nvoParamCmd.value[0] = 0
nvoParamCmd.value[1] = 0
nvoParamCmd.value[2] = 3 hex
nvoParamCmd.value[3] = 20 hex (800
decimal)
The controller node receives the following
parameter access response from the VLT.
nviParamResp.learn = LN_NULL
nviParamResp.selector = 201
nviParamResp.value[0] = 0
nviParamResp.value[1] = 0
nviParamResp.value[2] = 0
nviParamResp.value[3] = 3 (illegal data
value)
nviParamResp.day = 0
nviParamResp.hour = 0
nviParamResp.minute = 0
nviParamResp.second = 0
nviParamResp.millisecond = 0
The nviRequest.object_id should be set
to “1” (controller node). The network
uses nviRequest, nvoStatus and
nvoAlarm variables for these functions.
2. The VLT sends an
Object status
containing a bit map of supported
status fields in response to all other
Object requests,
including undefined
requests.
3. The VLT
Object status
supports the
following status fields: invalid_id,
invalid_request,open_circuit,
out_of_service, electrical_fault,
comm_failure, manual_control, and
in_alarm. All other fields are always
set to “0.”
4. The VLT sends an
Object alarm
following any set or reset of a drive
fault condition.
5. The
Object alarm
supports the
AL_ALM_CONDITION and
AL_NO_CONDITION alarm types.
Example 5:
