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Scope
Thank you for purchasing the model FT2A thermal gas mass flow meter from Fox Thermal.
The model FT2A is one of the most technically advanced flow meters in the world. Extensive
engineering effort has been invested to deliver advanced features, accuracy measurement
performance and outstanding reliability.
This document describes the BACnet MS/TP implementation using RS485 serial communication
physical layer for the Fox Thermal FT2A mass flow meter.
BACnet Protocol
BACnet MS/TP (Building Automation and Control Network /Master Slave Token Passing) is a
data link layer protocol designed for communication between devices in building automation
control systems. The protocol is based on devices, objects, properties, and services. Information
inside a BACnet device is organized into a series of objects. Properties allow the data from the
object to be written or read. The actions that a BACnet device uses to interact with another
device are the services.
The FT2A Device profile: BACnet Smart Sensor (B-SS)
FT2A supports the following device binding methods:
Receive Who-Is, send I-Am (BIBB DM-DDB-B)
Receive Who-Has, send I-Have (BIBB DM-DOB-B)
Objects for FT2A:
Analog Input 1 = Flow
Analog Input 2 = Gas Temperature
Analog Input 3 = Total Flow / Reset Total
Analog Input 4 = Elapsed Time since reset
Device object property identifiers and restrictions: (properties that are writable)
Object _Name
< 10 bytes
Object _ Identifier
Device Type only
Max _ info_ Frames
<=255
Max _ Master
<=127
BACnet Interoperability Building Blocks (BIBB’S) provide function capabilities for data exchange
between devices.
Modbus/BACnet
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BACNET Introduction
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