Sharing thermostats among Xenta 102-AXs (Master-Slaves)

[Product_Support]

Issue

How to share the thermostat data (room temperature, setpoints) among Xenta 102-AXs?

Product Line

TAC Vista, EcoStruxure Building Operation

Environment

Xenta 102-AX with or without plug-in

Cause

Using the wrong SNVT in Xenta 102-AX or sending the nvoEffectSetPt incorrectly will result in different unit behavior among Xenta 102-AXs.

Resolution

Assign the Xenta 102-AX wired with the thermostat to be the master (A), and other Xenta 102-AXs to be slaves (B to N). Use the built in SNVTs to transfer data from the master to slaves as shown in the diagram below.

Sharing space temperature

1. Bind master's nvoSpaceTemp to slaves' nviSpaceTemp.
2. Make sure set Node Minimum Send Time and Node Send Heartbeat to be a non-zero number. (Read more information in Values sent from a 102-AX via SNVT bindings are not making it to the receiving controller.)

Sharing setpoint

It is recommended to share the setpoint through the normalized nvoEffectSetpt in order to have the same unit behavior between the master and slaves. Read more information about how the nvoEffectSetPt is calculated and displayed in Xenta 102-AX Effective Setpoint (nvoEffectSetPt) Calculation.

The steps of sharing the setpoint among Xenta 102-AXs are listed below:

1. Set occupied/unoccupied heating and cooling setpoints on the master and slaves. The suggestion is to use the same setpoints setting on the master and slaves if want all rooms to operate in the same manner.
   
   In Xenta 102-AX plug-in
   1. Select Operating Parameters tab.
   2. Set the Cooling Setpoint and Heating Setpoint to desired value
   
   Without Xenta 102-AX plug-in
   1. Find SCPTsetPnts under VAV_Controller.
   2. Set the Cooling Setpoint and Heating Setpoint to desired values.
       
2. Set master's nviSetpoint under VAV_Controller to a desired temperature (eg. 72 °F or 22 °C).
    
3. Set the nvoEffectSetpt to be normalized.
   
   In Xenta 102-AX plug-in
   1. Select Operating Parameters or I/Stat Configuration tab.
   2. Under Effective Setpoint Source choose Norm of Heating and Cooling Setpoint
   
   Without Xenta 102-AX plug-in
   1. Find UCPTvavSelection.ESS under VAV_Controller
   2. Set UCPTvavSelection.ESS to 1. (Default is 0: Actual Setpoint).
       
4. Bind master's nvoEffectSetpt to slaves' nviSetPoint.
    
5. Make sure set Node Minimum Send Time and Node Send Heartbeat to be a non-zero number. (Read more information in Values sent from a 102-AX via SNVT bindings are not making it to the receiving controller.)

Additional Suggestions:

If the number of slaves is more than 30, it is better to tier up the transaction as shown below.