LON-bus and serial communication
General note
The control program has some standardized variables of type “SNVT” which permit the
communication with external units via LON-bus. There are input and output values. The input
values permit settings for the controller, which are directly available for the control process. The
output values indicate measuring values and status information of the unit.
Automatic update of variables
At each adjustment of the values in the controller the corresponding output variables are updated.
If there are no condition changes the values will be updated every “nciMaxSendTime” seconds. If
“nciMaxSendTime” is less than 1.0 sec. the values are no more updated in intervals but only if
there is any change.
(Therefore the following can occur: a master controller determines the setpoint of a slave
controller. The setpoint of the slave controller will be updated immediately if there is a change at
the master controller. If the setpoint is changed at the slave controller the “correct” value will be
send to the slave after “nciMaxSendTime” seconds.)
Adjustments of the input variables will be applied to the controller immediately and cause an
EEProm write access. Keep in mind the limited amount of save cycles.
Definition of the standard network variables
Object "Stufenschaltwerk"
Name of variable
Type
Input/Output
Values
Resolution
nviSetPointTemp
SNVT_temp_p Input
–273,17...327,66°C 0.01°C
nviSetPointPress
SNVT_press
Input
–32,768...32,767 bar or
–32768...32767 hPa
0.001 bar or
1 hPa
nviStandbyMode
SNVT_lev_disc Input
0...255
-----
nvoActualTemp
SNVT_temp_p Output –273,17...327,66°C 0.01°C
nvoActualPress
SNVT_press
Output
–32,768...32,767 bar or
–32768...32767 hPa
0.001 bar or
1 hPa
nvoRelayState
SNVT_state Output
On/Off
for
K1...K7 -----
nvoPowerPercent
SNVT_switch
Output
0...100 %, On/Off+error
0.5 %
nvoHrsCompr1
SNVT_time_hour
Output
0...65535 Std.
1 h
nvoHrsCompr2
SNVT_time_hour
Output
0...65535 Std.
1 h
nvoHrsCompr3
SNVT_time_hour
Output
0...65535 Std.
1 h
nvoHrsCompr4
SNVT_time_hour
Output
0...65535 Std.
1 h
nvoHrsCompr5
SNVT_time_hour
Output
0...65535 Std.
1 h
nvoHrsCompr6
SNVT_time_hour
Output
0...65535 Std.
1 h
Object "0"
Name of variable
Type
Input/Output
nvoStatus
SNVT_obj_status
Output
object status, see SNVT-list
nciNetConfig
SNVT_config_src
Input
configuration, see SNVT-list
nviRequest
SNVT_obj_request
Input
object request, see SNVT-list
Summary of Contents for ST710-PWHVM.26
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