AMX ViewStat - Manual (Page 52)

Using the NetLinx Module to Program the ViewStat
46 ViewStat Communicating Thermostat
It is important that the serial number array be the same length as the device array. If the serial number array
happens to be shorter, the length will be set to that of the device array and the new members of the array will be
set to the value 1. The two arrays are used to associate the ICSNet device number to the stat number of the
thermostats (set locally through the thermostat's user interface)
Upon initialization, the VST module will retrieve the current settings of all of the thermostats on the network.
This operation may take several seconds. During this time the NetLinx program will start receiving strings
representing the states of all of the thermostat's controls. The above default temperature scale is Fahrenheit.
The ViewStat Communicating Thermostat is an enhanced version of the OPStat with the communication board
built into the thermostat, advanced features and two displays. One display is for temperature, mode, limit
settings, lock status, fan status, network communication and humidity. The second display is used for general
text messaging for date, time, event status, and setup mode and user notifications.
The ViewStat can monitor remote temperature and humidity, has a flexible text mode setup and interface, and
has the ability to lock local control of the thermostat.
Care must be taken when attaching to remote sensors in that the remotes can turn the thermostat into a
humidity sensor that doesn't display the temperature in the main window. When acting as a humidity sensor,
the temperature can be retrieved through the control interface only. The remote temperature is displayed in
minor sections of the main window while the remote humidity inhabits the window center. When a remote
sensor is attached, humidity changes do not generate a Change Of State message. Also, as a humidity sensor,
the mode button will change from humidity to dehumidify and report accordingly over the control interface. To
retrieve humidity, there is a conditional poll generated upon temperature events if the temperature event came
from a humidity-supported device.
The VST_ZoneCnt is used to affect the wait period between successive commands being sent to the
thermostats. The larger the VST_ZoneCnt value is, the longer the time delay between global commands
becomes. The VST_ZoneCnt variable is associated with the serial number of a thermostat.
To install the ViewStat module, the developer must create an array of devices and an array of integers that
stand for the serial number of the thermostat corresponding to the physical ICSNet device. Unless otherwise
needed, the serial number of all thermostats should be set to '1', to allow the quickest response from the
thermostat on global commands.
ViewStat also provides feedback from its local buttons: enter, scroll up, and scroll down. This allows the
control system to track the menu navigation if desired.
The following diagram gives a graphical view of the interface between the NetLinx program and the NetLinx
module.
The ViewStat Model
The model will define a security system as consisting of the following components:
1. System: This refers the controller and all that it controls.
2. Zone: The system will consist of one or more ViewStat zones. A zone is nothing more than an area that
can be controlled separate from other areas. Zones have their own temperature settings.
3. Thermostat: Each zone contains a thermostat. The thermostat is used for reading temperature and
controlling when to turn on/off equipment as needed to maintain the desired temperature setting.
Thermostats can control fans, heat, A/C., etc.
4. Setpoint: There are two types of setpoints: heat and cool. When the temperature reaches or falls below
the heat setpoint the thermostat will turn the heat on (call for heat). When the temperature reaches or
exceeds the cool setpoint the thermostat will turn the air conditioner on (call for air). These are also called
comfort points. A user can keep the temperature within these points at all times by setting the setpoint
values. For example, to maintain a temperature of 68-72 degrees the heat setpoint would be set to 68, the
FIG. 39 Interface between the NetLinx program and the NetLinx module.
NetLinx
Program
NetLinx
Module
ViewStat
Controller Virtual
Device