Trane Engineered Smoke Control System for Tracer Summit manual Network variable bindings, Overview

Chapter 8

Network variable bindings

Overview

The LonTalk communications protocol allows data to be shared between devices (stand-alone or with a BAS) on a LonTalk network. This is called peer-to-peer communication. As an example of peer-to-peer communica- tion, two or more devices serving the same space share data, such as a temperature reading, without having to pass the data through a BAS.

Network variables are used to share data between devices. The method used to direct data from one device to another is called network variable binding, or just binding. A network variable output from one device is bound to a network variable input on another device. An output variable from one device can be bound to input variables on many other devices.

Binding network variables

Each network variable is a standard type. This standard type is referred to as a standard network variable type (SNVT). To bind two variables together they must be the same SNVT. For example, an output of type SNVT_temp_p can only be bound to an input of type SNVT_temp_p. For more information about SNVTs, see the LonMark™ Web site (www.lon- mark.org). From that Web site you can download the official list of SNVTs.

IMPORTANT

Only LonTalk devices can use network variable binding. Devices on other communications links do not have this capability.

BAS communications typically do not require the use of network variable binding because a Tracer Summit BCU will automatically bind to the proper data in a device. However, communications speed may be increased between two devices by binding their data rather than having the BAS read the information from one device and then broadcast it to another.

Use the Rover service tool to create bindings. (See the Rover Operation and Programming guide, EMTX-SVX01E-EN.)

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