No more address table slots for a device involved in the attempted connection. (Subsystem: NS Connections, #15)

[Product_Support]

Issue

No more address table slots for a device involved in the attempted connection. (Subsystem:  NS Connections, #15)

Product Line

TAC Vista

Environment

LonMaker 3.X

NS Connections Error codes are not specific to any one LON environment, the display of the error may vary, but the steps to resolve should be the same.
 

Cause

Every LON Neuron chip has 15 total address table slots inside, which store addressing information for SNVT communication.  Xenta programmable controllers utilize Address Table slots 0 and 1 for TAC and Xenta Group Binding information for reporting online status to the Vista Server and transferring TA Network Variables to each other.  This leaves 13 available address table slots in a Xenta programmable controller.  There are many scenarios by which address table slots are consumed (both in the sending and receiving controllers).  If you have exceeded the address table limitations, no further SNVT bindings (which would require additional address table slots) will be allowed.
 

Resolution

The error message should indicate which controller has exceeded its address table limitations (sending or receiving).  First verify the current status of the address table.

1. Right-click on the controller
2. Select Properties
3. Navigate to the Address Table tab.
   
   
4. This will tell you (a) if the address table is indeed full or (b) how many slots you have left.  Knowing this can help you determine the easiest recourse to the problem.

If the address table is full in the sending controller:

1. Information can only be sent via one-to-one bindings to 15 controllers (13 from a Xenta programmable).  Sometimes combining data into a one-to-many can save address table slots.  Instead of sending an individual occupancy to 20 VAVs, which consumes 20 address table slots, send them all the same one-to-many occupancy command, which consumes only 1 address table slot.
2. Using a broadcast SNVT binding type will save on address table slots by only consuming one slot per receiving subnet instead of one per receiving controller.  This will increase network bandwidth, but allows one-to-one bindings to many controllers in the same subnet.  Xenta programmable SNVT output limits would be the only limiting factor.
   
   See Bind to more than 13 unique LON devices without running out of address table entries for details on creating Broadcast SNVT Bindings.

If the address table is full in the receiving controller:

1. If the binding is a one-to-one binding type:
   1. This is typically not an issue. The receiving controller does not normally have an address table slot consumed by a one-to-one SNVT binding. The only time a receiving controller has an address table slot consumed by a one-to-one SNVT binding is if that SNVT input is set to ""Poll."" (Unacknowledged, repeated, acknowledged profiles have no bearing on the number of address table slots consumed by one-to-one bindings.)
      
      
   2. Unless dictated by the manufacturer of the device with which you are integrating, it is very rare to require polled inputs in a Menta file. Check the SNVT AI blocks in Menta and uncheck the "Poll" checkbox. Binding these inputs will no longer consume an address table slot in the receiving controller.
2. If the binding is a one-to-many group binding type:
   1. Every member of the binding (sending or receiving) will have at least one address table slot consumed by the group binding. Freeing up address table slots may require some creative manipulation of the bindings. Options are:
      • Convert to one-to-one bindings where the receiving controller will not lose an address table slot
      • Do not customize every individual combination of group bindings (i.e. send the setpoint to the same controllers that are receiving outside air temp, even if they won't be using it). Every unique combination of controllers will constitute a new group and thus consume a new address table slot in each controller.