Trane BAS-APG001-EN manual Stacking bindings on unique binding paths, Network variable bindings

Chapter 8 Network variable bindings

A unique subnet/node binding type is a specific path from device X to device Y. Any number of actual network variable bindings could be built upon this path (see below). Regardless of the number of bindings built on a given path, only one address table entry will be consumed on the sending device. Note that this rule applies to subnet/node bind- ings that are part of one-to-one binding shapes or fan-in binding shapes.

3.Unique group binding types consume an address table entry on all devices in the group.

A unique group binding type is a specific fan-out path from device X to a specific set of target devices (for example, Y and Z). Any number of actual network variable bindings could be built upon this path (see below). If another sending device and/or another set of target devices is necessary, a new group is needed and another address table entry will be consumed in each group member.

4.Each LonWorks device has a maximum of 15 address table entries.

This limit applies to all LonWorks devices: Neuron-based devices, host-based devices (including the BCU), and hybrid devices. Note that the Tracer VV550/551 is an exception; it has only 14 available address table entries.

5.A maximum of 256 groups are possible per domain. This limit should not be a factor in most designs.

6.A group binding that uses acknowledged service can have a maximum of 64 members. A group binding that uses unacknowledged or unacknowledged repeated service can have an unlimited number of members.

Stacking bindings on unique binding paths

Once a binding has been created, a unique path exists that is defined in the address tables. It is important to understand that these unique paths can be reused by additional bindings without consuming additional address table entries.

A unique path is possible for subnet/node binding types (one-to-one or each piece of a fan-in) and group binding types (fan-out). A unique path is defined by a sending hub and a specific set of receiving target devices.

The simplest unique path is that shown in Figure 74. The three bindings below will consume one entry, the domain/subnet/node of MP581-B, in MP581-A’s address table. They will not consume any entries in MP581- B’s address table. Only MP581-A is the transmitter in this example. This is a subnet/node binding. A good analogy would be that the road between MP581-A and MP581-B has already been laid down (in one direction). Any other information needed to flow between those two devices has a well defined route already available.

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