Driver Manual
Supplement to the FieldServer Instruction Manual)
FS-8704-02 BACnet Ethernet

APPLICABILITY & EFFECTIVITY
Effective for all systems manufactured after May 2009

Driver Version: 1.17

Document Revision: 1

 

1. BACNET ETHERNET DESCRIPTION

The BACnet Ethernet driver allows the FieldServer to transfer data to and from devices over Ethernet using BACnet Ethernet protocol. The FieldServer can emulate either a Server or Client.

All information in a BACnet system is represented in terms of objects. The Object_Identifier is a 32-bit code that identifies the type of Object (also identified by the Object_Type Property) and its "Instance" number, which together uniquely identify the Object within its BACnet device. Theoretically, a BACnet device could have over four million Objects of a particular type. The Object_Name is a text string, which has a unique capability. BACnet devices may broadcast queries for devices that contain Objects with a specific Object_Name. This can greatly simplify project setup.

BACnet requires one Device Object to be present in every BACnet device. The Device Object makes information about the device and its capabilities available to other devices on the networks. Before one BACnet device starts control-related communications with another, it needs to obtain some of the information presented by the other device's Device Object. Unlike other Objects, the Device Object's Instance number must be unique across the entire BACnet internetwork because it is used to uniquely identify the BACnet devices. It may be used to conveniently identify the BACnet device from other devices during installation.

Standard object types are used to hold real time data and other information. Each Object Type is referenced by a number, for example 0 represents an Analog Input.

Each Object consists of a number of prescribed properties, the main property being the Present_Value. Objects are monitored and controlled through their properties. The Analog Input Object is representative of the Objects involved directly with control elements and many of its Properties reflect this.

The information that follows describes how to expand upon the factory defaults provided in the configuration files included with the FieldServer.

 

2. DRIVER SCOPE OF SUPPLY

2.1  Supplied by FieldServer Technologies for this driver

 

FieldServer Technologies PART #	2nd Cell
FS-8915-10	UTP cable (7 foot) for Ethernet connection1

 

2.2 Provided by the Supplier of 3 rd Party Equipment

2.2.1 Hardware

 

Part #	Description
	Ethernet 10/100 BaseT hub2
Trane Building Control Unit (BCU)	Building control unit (BCU) with internal Ethernet adapter.

 

1This cable is necessary for connection to the driver. It is shipped with the FieldServer and not separately with the driver.

2Not all FieldServer models support 100BaseT. Consult the appropriate instruction manual for details of the Ethernet speed supported by specific hardware.

 

3. HARDWARE CONNECTIONS

It is possible to connect a BACnet/IP device using the N1 or the N23  network ports. These ports need to be configured for BACnet/IP in the configuration file.

Configure the Controller according to manufacturer's instructions.

 

 

3Not all ports shown are necessarily available on the hardware. Consult the appropriate Instruction manual for details of the ports available on specific hardware.

 

4. CONFIGURING THE FIELDSERVER AS A BACNET ETHERNET CLIENT

For a detailed discussion on FieldServer configuration, please refer to the FieldServer Configuration Manual. The information that follows describes how to expand upon the factory defaults provided in the configuration files included with the FieldServer (See ".csv" sample files provided with the FieldServer).

This section documents and describes the parameters necessary for configuring the FieldServer to communicate with a BACnet Ethernet Server.

The configuration file tells the FieldServer about its interfaces, and the routing of data required. In order to enable the FieldServer for BACnet Ethernet communications, the driver independent FieldServer buffers need to be declared in the "Data Arrays" section, the destination device addresses need to be declared in the "Client Side Nodes" section, and the data required from the Servers needs to be mapped in the "Client Side Map Descriptors" section. Details on how to do this can be found below.

 

4.1  Data Arrays/Descriptors

Note that in the tables, * indicates an optional parameter, with the bold legal value being the default.

 

Section Title
Data_Arrays
Column Title	Function	Legal Values
Data_Array_Name	Provide name for Data Array	Up to 15 alphanumericcharacters
Data_Array_Format	Provide data format. Each Data Array can only take on one format.	Float, Bit, Uint16, Uint32, Sint16, Sint32, Packed_Bit, Byte, Packed_Byte, Swapped_Byte, AI, AV, AO, BI, BV, BO
Data_Array_Length	Number of Data Objects. Must be larger than the data storage area required by the Map Descriptors for the data placed in this array.	1-10,000

 

Example

 

 

4.2  Client Side Connection Descriptions

Section Title
Connections
Column Title	Function	Legal Values
Adapter	Adapter Name	N1, N24
Protocol	Specify protocol used	BACnet_Eth
Poll_Delay*	Time between internal polls	0-32000s; 0.25s

 

Example

 

4.3  Client Side Node Descriptors

Section Title
Nodes
Column Title	Function	Legal Values
Node_Name	Provide name for Node	Up to  32 alphanumericcharacters
Node_ID	BACnet device identifier of physical Server Node	1 – 16777215
Protocol	Specify protocol used	BACnet_Eth
Adapter	Specify port Adapter used	N1, N24

 

Example

 

 

4Consult the appropriate Instruction manual for details of the ports available on specific hardware.

 

4.4 Client Side Map Descriptors

4.4.1 FieldServer Related Map Descriptor Parameters

 

Section Title
Map Descriptors
Column Title	Function	Legal Values
Map_Descriptor_Name	Name of this Map Descriptor. This is used for Object_Name Property. Refer to Appendix A.1.	Up to  32 alphanumericcharacters
Data_Array_Name	Name of Data Array where data is to be stored in the FieldServer	One of the Data Array names from "Data Array" section above
Data_Array_Offset	Starting location in Data Array	0 to ("Data_Array_Length" -1)
Function	Function of Client Map Descriptor	Rdbc, Wrbc, Wrbx, Ars

 

4.4.2 Driver Related Map Descriptor Parameters

Section Title
Map Descriptors
Column Title	Function	Legal Values
Node_Name	Name of remote Server Node.	One of the Node_Names specified in "Client Side Node Descriptors" above
Object_Type(Alias = Data_Type)	Type of object. Refer to Appendix D.1 for more information.	AI, AO, AV, BI, BO, BV, MI, MO, MV, NC
Object_Instance(Alias = Address)	Instance of the object on the device.	0, 1, 2, 3, …4194303
Property	The BACnet property to be read.	Refer to Appendix D.2
Data_Array_Low_Scale*	Scaling zero in Data Array	-32767 to 32767,  0
Data_Array_High_Scale*	Scaling max in Data Array	-32767 to 32767,  100
Node_Low_Scale*	Scaling zero in Connected Node	-32767 to 32767,  0
Node_High_Scale*	Scaling max in Connected Node	-32767 to 32767,  100
Length*	Used to create an array of sequential Object_Instances on an Object_Type.	1 to max point count of the FieldServer,1
Array_Index*	When referencing Multistate properties, allows the user to specify the index of the property to be read. If 1 is specified, the first one will be read, if 2 is specified, the second will be read, etc. If 0 is specified, the driver will return the total number (count) of array items linked to the property. If the parameter is not specified, a list of all items will be returned. Refer to Appendix A.3	0 to max number of array items in the BACnet Property, –

 

4.4.3 Timing Parameters

Section Title
Map Descriptors
Column Title	Function	Legal Values
Scan_Interval*	Rate at which data is polled	0-32000s,  2s

 

4.4.4 Map Descriptor Examples

 

 

5. CONFIGURING THE FIELDSERVER AS A BACNET ETHERNET SERVER

For a detailed discussion on FieldServer configuration, please refer to the FieldServer Configuration Manual. The information that follows describes how to expand upon the factory defaults provided in the configuration files included with the FieldServer (See ".csv" files provided with the FieldServer).

This section documents and describes the parameters necessary for configuring the FieldServer to communicate with a BACnet Ethernet Client

The configuration file tells the FieldServer about its interfaces, and the routing of data required. In order to enable the FieldServer for BACnet Ethernet communications, the driver independent FieldServer buffers need to be declared in the "Data Arrays" section, the FieldServer virtual node(s) needs to be declared in the "Server Side Nodes" section, and the data to be provided to the Clients needs to be mapped in the "Server Side Map Descriptors" section. Details on how to do this can be found below.

Note that in the tables, * indicates an optional parameter, with the bold legal value being the default.

 

5.1  Driver Specific FieldServer Parameters

Section Title
Bridge
Column Title	Function	Legal Values
Title	FieldServer name	Text
Network_Number*	Speify a unique network number if there are multiple virtual Server Nodes. Refer to Appendix A.2	1 – 65535,  5

 

Example

 

 

5.2  Data Arrays

Section Title
Data_Arrays
Column Title	Function	Legal Values
Data_Array_Name	Provide name for Data Array	Up to 15 alphanumericcharacters
Data_Array_Format	Provide data format	Float, Bit, Uint16, Uint32, Sint16, Sint32, Packed_Bit, Byte, Packed_Byte, Swapped_Byte, AI, AV, AO, BI, BV, BO
Data_Array_Length	Number of Data Objects	1-10,000

 

Example

 

 

5.3   Server Side Connection Descriptors

Section Title
Connections
Column Title	Function	Legal Values
Adapter	Adapter Name	N1, N25
Protocol	Specify protocol used	BACnet_Eth

 

Example

 

 

5.4  Server Side Node Descriptors

Section Title
Nodes
Column Title	Function	Legal Values
Node_Name	Provide name for Node	Up to  32 alphanumericcharacters
Node_ID	BACnet station address of physical Server node	1 – 16777215
Protocol	Specify protocol used	BACnet_Eth
Node_Option*	Enable or disable COV for this Node. Refer to Appendix A.6 for further information.	COV_Enable, COV_Disable, –

 

5  Not all ports shown are necessarily supported by the hardware. Consult the appropriate Instruction manual for details of the ports available on specific hardware.

6  Note that no connection information is necessary on Server side.

 

Example

 

 

5.5  Server Side Map Descriptors

5.5.1 FieldServer Specific Map Descriptor Parameters

 

Section Title
Map_Discriptor
Column Title	Function	Legal Values
Map_Descriptor_Name	Name of this Map Descriptor. This is used for Object_Name Property. Refer to Appendix A.1.	Up to  32 alphanumericcharacters
Data_Array_Name	Name of Data Array where data is to be stored in the FieldServer	One of the Data Array names from "Data Arrays" section above
Data_Array_Offset	Starting location in Data Array	0 to ("Data_Array_Length" -1)
Function	Function of Server Map Descriptor	Server

7Note that adapter is not declared under Server Side Nodes.

 

5.5.2 Driver Specific Map Descriptor Parameters

 

Section Title
Map Descriptors
Column Title	Function	Legal Values
Node_Name	Name of Node to fetch data from	One of the Node Names specified in "Server Side Node Descriptors" above
Object_Type(Alias = Data_Type)	Data type in Controller	AI, AO, AV, BI, BO, BV, MI, MO, MV, NC. Refer to Appendix D.1.
Object_Instance(Alias = Address)	Instance of the Object on the Device.	0, 1, 2, 3, …4194303
Units*	The object units	Refer to Appendix D.3,  No-Units
Data_Array_Low_Scale*	Scaling zero in Data Array	-32767 to 32767,  0
Data_Array_High_Scale*	Scaling max in Data Array	-32767 to 32767,  100
Node_Low_Scale*	Scaling zero in Connected Node	-32767 to 32767,  0
Node_High_Scale*	Scaling max in Connected Node	-32767 to 32767,  100
Active_Text *8	Specify the Active Text property of the Object	Any text string of length up to 40 characters,  Active
Inactive_Text *8	Specify the Inactive Text property of the Object	Any text string of length up to 40 characters,  Inactive
Relinquish_Default8	Specify the value to be returned as Present_Value on startup or when control is relinquished. Must be specified for outputs. Refer to Appendix D.2	Any Float value
Length*	Used to create an array of sequential Object_Instances on an Object_Type.	1 to max point count of the FieldServer,  1
Notification_Class*	Specify the Mapdescriptor_Name of the Notification_Class Object that manages Intrinsic Reporting for this Map Descriptor. Refer to Appendix A.6.	Oneoftheconfigured Mapdescriptor_Names of type NC (Notification Class). Objects are not available to any NC if left out.
Ack_Required*	For a Notification_Class Object, specify whether EventNotifications require a user Acknowledgement. Refer to Appendix A.6.	Yes,  No
COV_Increment*	For a Server Map Descriptor of type AO or AI, initialize the COV_Increment property. Refer to Appendix A.6.	Any Float value,  0
Input_alarm_State*	For binary points the user can specify which of the states (0 or 1) to regard as an alarm state.	0,  1
Description*	Specify the object's description property. Eg Room Temp – Refer to Appendix A.6.3	Any text string of length up to 40 characters, If not configured, defaults to Object_Name.

 

5.5.3 Map Descriptor Example

 

Appendix A. Useful Features

 

Appendix A.1. BACnet object names

When an external BACnet Client builds a list of Object Names, the BACnet Server Map Descriptor names determine the BACnet Object Name. If the Map Descriptor length is greater than 1, the Object Name will be suffixed with the index into the Map Descriptor. For example, if the Map Descriptor name is SMD_AI_01 and the length 3, then the Object Names will be SMD_AI_01[0], SMD_AI_01[1] and SMD_AI_01[2].

 

Appendix A.2. Network number

If multiple BACnet Nodes are specified on the Server side, the FieldServer automatically defaults to virtual operation. In effect, the FieldServer simulates a software router. BACnet identifies this ieldServer using a combination of it's network number and IP/MAC address. The default Network number of a FieldServer is 5. If there is more than one FieldServer on a BACnet intranet with multiple nodes, the default network number of the additional FieldServers will need to be changed and a unique number allocated to each.

A unique network number will need to be assigned if both of the following conditions are true:

 

• The FieldServer has multiple BACnet Server nodes.
• There is more than one FieldServer on a network which includes multiple BACnet nodes.

To override the FieldServer's default network number 5 include the following in the configuration file:

Section Title
Bridge
Column Title	Function	Legal Values
Title	FieldServer name	Text
Network_number*	Specify a unique network number if there are ultiple virtual Server nodes.	1-65534,  5

 

Example

 

 

Note: While it is theoretically possible to have up to 65535 virtual nodes, it is recommended that a maximum of 35 is configured. If an application requires the configuration of more than 35 virtual nodes please consult FST.

 

Appendix A.3. Accessing Data from BACnet Properties comprising Arrays of Values

Some BACnet Object properties (e.g. Priority_Array) are arrays of values (the Priority_Array property is an array of 16 values). In order to read a specific array entry, the rray_Index must be specified in the Map Descriptor. Array_Index is a Client Side Map Descriptor function

The following example shows a configuration that will read the Priority_Array value at Array_Index 7, belonging to Analog Output 1.

 

Details of the relevant BACnet properties and their associated arrays can be found in the BACnet Protocol Spec.

 

Appendix A.4. FieldServer implementation of BACnet priority Arrays

When BACnet Output objects are written to the Server side of the FieldServer, an associated write priority is given to each write value. When the FieldServer receives the write value, it stores it to the Map Descriptor Priority Array Table at the specified priority. The Priority Array Table is then scanned and the value with the highest priority is stored to the Data Array location specified by the Map Descriptor.

When a Write "Relinquished" command is received, the value is removed from the Priority Array Table and the next highest value from the Priority Array Table is stored to the Data Array.

If all values have been "Relinquished" from the Priority Array Table, then the Map Descriptors "Relinquish Default" value will be stored to the Data Array.

 

Appendix A.4.1. Accessing Priority Array information

The Priority Array table and its "In_Use" (or Not Relinquished) state are stored internally to every Map Descriptor, and cannot be accessed directly. The information can be accessed indirectly by specifying the following Data Arrays which will maintain an exact copy of the Priority Array Table for the Map Descriptor.

Section Title
Map_Descriptor
Column Title	Function	Legal Values
DA_Pri_Array	Name of Data Array where the Priority Array Table will be stored. Location 0 is the Relinquish Default value and locations 1 to 16 the different entries of the Priority Array Table.	Up to 16 alphanumericcharacters
DA_Pri_Array_Offset*	Starting location in Data Array.	1-65535,  0
DA_Pri_In_Use	Name of Data Array that indicates if a particular Priority Value is in use. Location 0 indicates whether the Relinquish Default has been set and locations 1 to 16 indicate whether the index is in use (1), or Relinquished (0).	Up to 16 alphanumericcharacters
DA_Pri_In_Use_Offset*	Starting location in Data Array.	1-65535,  0

 

Appendix A.5. BACnet State Text Preload

BACnet Multistate Objects have a State_Text property. This property is defined as an array of character strings representing descriptions of all possible states of the Present_Value. The number of descriptions matches the number of states defined in the Number_Of_States property. The Present_Value, interpreted as an integer, serves as an index into the array.

When Multistate Objects are configured on a BACnet server it is necessary to define the State_Text property. This section illustrates how to define the State_Text character strings and how to associate these definitions with Multistate Server Map Descriptors.

The maximum permitted length of any State_Text string is 50 characters.

 

Appendix A.5.1.  Method 1 – Using an Offset/User Table:

 

Appendix A.5.2.  Method 2 – Using a Single Data Array:

 

Appendix A.5.3.  Using Intrinsic Reporting for a Multistate Value

To use Intrinsic Reporting for a Multistate value, it is necessary to classify each of the states as either Normal, Alarm or Trouble. This is done by adding another column to the Offset_Table, called Table_User_Value. Each state is then classified by inserting one of the following values in its row:

 

0 = normal

1 = alarm

2 = fault

 

 

 

Note:  The state value (Table_Index_Value) is an enumerated value greater than zero. Zero is not a valid value, but since many client side configurations will wake up with values of zero, the BACnet server will treat a value of zero as a normal value (i.e. not as an alarm or fault value)

 

Appendix A.6. COV and Intrinsic Reporting

The COV and Intrinsic Reporting services are two distinct ways in which point values can be reported to a client workstation as they change, i.e. in an event-driven opposed to a polling method. This can increase performance dramatically compared to polling method alone. It also reduces network traffic significantly.

The services are suited to different purposes:

• COV is suited to value updates. On analog points the sensitivity can be set using the COV_Increment property. Only changes larger than the COV_Increment value will be reported.
• Intrinsic Reporting is used for alarming. It is implemented via Notification_Class objects, which can receive subscriptions from client workstations that add themselves to the RecipientList property of a Notification_Class object.Notifications are done using ConfirmedEventNotification or UnconfirmedEventNotification. Intrinsic Reporting also allows for alarms to be acknowledged and for all subscribed client workstations to be notified of alarm acknowledgements.

 

Appendix A.6.1.  Notes on COV configuration:

• No special configuration entries are needed to enable COVs. The service is enabled by default for all protocols except MSTP. Most client workstations will automatically subscribe to all points once they
• discover that the FieldServer supports COV services. This only applies to BACnet Objects – Property subscribes are not supported by the FieldServer.
• The Node_Option parameter can be configured to enable or disable COV. An example configuration is presented in Appendix A.6.5
• For analog Server Map Descriptors the user may optionally configure a COV_Increment value to adjust the reporting threshold. If it is not set the COV_Increment defaults to zero.
• Change of Value (COV) Notifications are generated for all data objects for which a remote client has issued a SubscribeCOV-Request. The SubscribeCOV-Request regulates whether Notifications are Confirmed or Unconfirmed. The remote client may also write the COV_Increment property in order to control the deadband for changes in analog values. The COV_Increment property can be initialized via  the configuration file by setting the COV_Increment Map Descriptor Property. The value set by the configuration is an initial value that is loaded on startup. It would be replaced by any new value written by the Client
• COV is not available on the ProtoCessor

 

Appendix A.6.2.  Notes on Intrinsic Reporting configuration:

• Intrinsic Reporting is managed by Notification Class objects. At least one Notification Class object must be configured for Intrinsic Reporting to work.
• Each Data_Object that is to be monitored by Intrinsic Reporting must be linked to a Notification Class object via the Notification_Class Map Descriptor Property. For analog points alarm limits must be set up, and for binary points, the Input_Alarm_State must be set up.
• The Notification_Class object contains properties that allow a client workstation to modify rules governing event reporting, such as event_type, days of week, start and end times etc.
• The RecipientLists are non-volatile, and subscriptions must be renewed on system restart.

 

Appendix A.6.3.  Map Descriptor Example – COV

 

Appendix A.6.4.  Map Descriptor Example – Intrinsic Reporting

 

Appendix A.6.5.  Map Descriptor Example – Enable or Disable COV

Appendix B. Troubleshooting

• If duplicate Object_Instances are configured in the FieldServer, the second call of the Instance will overwrite the first one. This may cause a BACnet Object to be "lost."
• If "Virtual_BCU_…" is not being indicated as the device description for the FieldServer on the BACnet SCADA system, then the FieldServer is not communicating with the SCADA system. If the Present_Value's name is being indicated, but the Present_Value shows question marks, then it is likely that the Client side of the FieldServer is not communicating.
• Some of the BACnet IP features result in the creation of files (priarray.ini; desc.ini; alarms.ini) on the FieldServer. Sometimes updates of firmware can result in these files becoming outdated. Deleting these files will restore configuration defaults and may assist with configuration errors.
• Extra memory is required to store Map Descriptors that have the active/inactive text parameters specified. If the defaults are appropriate, do not specify these parameters. This will save memory and allow more Map Descriptors to be created

Appendix C. Vendor Information

Appendix C.1. McQuay

McQuay Units are shipped with a default Device instance of the last 6 digits of the McQuay Serial number.

 

Appendix C.2. Trane

When new points are added to the FieldServer it is important to restart the Summit Workstation or BCU, otherwise these new points may not be seen by the FieldServer.

Disconnect the FieldServer from the BACnet network when transferring images to the BCU.

 

Appendix C.3. Liebert

Polling BACnet addresses that are not configured for Liebert systems may cause the connection to fail in older versions of Liebert. Please contact your Liebert supplier for more information.

Appendix D. Reference

Appendix D.1. Object_Type Legal Values – Abbreviation Descriptions

AI	ANALOG_INPUT
AO	ANALOG_OUTPUT
AV	ANALOG_VALUE
BI	BINARY_INPUT
BO	BINARY_OUTPUT
BV	BINARY_VALUE
MI	MULTI_STATE_INPUT
MO	MULTI_STATE_OUTPUT
MV	MULTI_STATE_VALUE
NC	NOTIFICATION_CLASS_OBJECT

 

 

Appendix D.2. Property Legal Values

Legal Value	Description
Object_Identifier	This property is a numeric code that is used to identify the object. It is unique within the BACnet Device that maintains it.
Object_List	Relevant to Device Object Type. This property is a BACnetARRAY of Object_Identifiers, one Object_Identifier for each object within the device that is accessible through BACnet services. An Object_Identifier is composed of Object Type and Object Instance and must be unique within a BACnet Device, e.g. Object Type = Analog Input, Object Instance = 3
Present_Value	This property contains the present value of the Input / Output / Value
Object_Name	Character string providing the name of a BACnet object. The set of characters used in the Object_Name is restricted to printable characters. The Object_Name is determined by the Map_Descriptor_Name.
Description	Character string describing a BACnet object. This can be defined by the user to give additional detail about the Object.
Out_of_service	The Out_Of_Service property, of type BOOLEAN, is an indication whether (TRUE) or not (FALSE) the physical input that the object represents is not in service. This means that the   Present_Value property is decoupled from the physical input and will not track changes to the physical input when the value of Out_Of_Service is TRUE. In addition, the Reliability property and the corresponding state of the FAULT flag of the Status_Flags property shall be decoupled from the physical input when Out_Of_Service is TRUE. While the Out_Of_Service property is TRUE, the Present_Value and Reliability properties may be changed to any value as a means of simulating specific fixed conditions or for testing purposes. Other functions that depend on the state of the Present_Value or Reliability properties shall respond to changes made to these properties while Out_Of_Service is TRUE, as if those changes had occurred in the physical input.
Event_State	The Event_State property, of type BACnetEventState, is included in order to provide a way to determine if this object has an active event state associated with it. If the object supports intrinsic reporting, then the Event_State property shall indicate the event state of the object. If the object does not support intrinsic reporting, then the value of this property shall be NORMAL. Other values: FAULT, OFF-NORMAL, HIGH-LIMIT, LOW-LIMIT, LIFE-SAFETY-ALARM
Units	This property contains the units associated with the Present_Value property.
Reliability	The Reliability property, of type BACnetReliability, provides an indication of whether the Present_Value or the operation of the physical input in question is "reliable" as far as the BACnet Device or operator can determine and, if not, why. The following values are supported: NO_FAULT_DETECTED, UNRELIABLE_OTHER.
Priority_Array	This property relates to Output and Value Object Types and is a read only array that contains prioritized commands or NULLs in the order of decreasing priority. The highest priority (lowest array index) with a non-NULL value is the active command.
State_Text	Relevant to Multistate Object Types: This property is a BACnetARRAY of character strings representing descriptions of all possible states of the Present_Value. The number of descriptions matches the number of states defined in the Number_Of_States property. The Present_Value, interpreted as an integer, serves as an index into the array.
Number_Of_States	Relevant to Multistate Object Types: this property sets the total number of states for which descriptions will be returned as defined under the State_Text property. The number of states will be determined automatically by the largest state number used when configuring the Offset Table (Refer to Appendix A.5).
Max_Master	Relevant to BACnet MS/TP Device Object Type: The Max_Master property, of type Unsigned, shall be present if the device is a master node on an MS/TP network. The value of Max_Master specifies the highest possible address for master nodes and shall be less than or equal to 127. If the Max_Master property is not writeable via BACnet services, its value shall be 127.
Max_Info_Frames	Relevant to BACnet MS/TP Device Object Type: The Max_Info_Frames property, of type Unsigned, shall be present if the device is a node on an MS/TP network. The value of Max_Info_Frames specifies the maximum number of information frames the node may send before it must pass the token. If Max_Info_Frames is not writable or otherwise user configurable, its value shall be 1.
Active_Text	Relevant to Binary Object Types: This property, of type CharacterString, characterizes the intended effect of the ACTIVE state of the Present_Value property from the human operator's viewpoint. The content of this string is a local matter, but it is intended to represent a human-readable description of the ACTIVE state. For example, if the physical input is a switch contact, then the Active_Text property might be assigned a value such as "Fan 1 On".
Inactive_Text	This property, of type CharacterString, characterizes the intended effect of the INACTIVEstate of the Present_Value property from the human operator's viewpoint. The content of this string is a local matter, but it is intended to represent a human-readable description of the INACTIVE state. For example, if the physical input is connected to a switch contact, then the Inactive_Text property might be assigned a value such as "Fan 1 Off".
Description	A character string giving more information about the Object associated with the Present_Value property.
Firmware_revision	The firmware revision of the application.
Relinquish_Default	This property is the default value to be used for the Present_Value property when all command priority values in the Priority_Array property have a NULL value.

 

Appendix D.3 Units

Unit	Variation 1	Variation 2	Variation 3
Amperes	Amps	A
Bars
BTUs
BTUs-per-hour
btus-per-pound
btus-per-pound-dry-air
centimeters
centimeters-of-mercury
centimeters-of-water
cubic-feet
cubic-feet-per-minute
cubic-feet-per-seconds
cubic-meters
cubic-meters-per-hour
cubic-meters-per-seconds
Currency1
Currency2
Currency3
Currency4
Currency5
Currency6
Currency7
Currency8
Currency9
Currency10
cycles-per-hour
cycles-per-minute
days
degrees-angular
Degrees-Celsius	Deg-C	Deg_C
degrees-Celsius-per-hour
degrees-Celsius-per-minute
Degrees-days-Celsius
Degrees-days-Fahrenheit	Deg-F	Deg_F
Degrees-Fahrenheit
degrees-Fahrenheit-per-hour
degrees-Fahrenheit-per-minute
Degrees-Kelvin	Deg-K	Deg_K
degrees-phase
delta-degrees-Fahrenheit
delta-degrees-Kelvin
feet
feet-per-minute
feet-per-second
foot-candles
grams-water-per-kg-dry-air
hectopascals
Hertz	Hz
Horsepower	HP
hours
imperial-gallons
imperial-gallons-per-min
inches
inches-of-mercury
inches-of-water
Joules
joules-per-degree-kelvin
joules-per-kilogram-degree-kelvin
joules-per-kilogram-dry-air
Kilograms	Kg
kilograms-per-hour
kilograms-per-minute
kilograms-per-second
Kilohertz	KHz
kilohms
Kilojoules
kilojoules-per-kilogram
kilometers-per-hour
kilopascals	KPa
kilovolt-amperes	kilovolt-amps	KVA
kilovolt-amperes-reactive	KVAR
kilovolts
kilowatt-hour-per-square-foot
kilowatt-hour-per-square-meter
kilowatt-hours	KWh
kilowatts	KW
liters
liters-per-hour
liters-per-minute
liters-per-second
lumens
luxes
Megahertz	MHz
megajoules
megajoules-per-square-foot
megajoules-per-square-meter
megavolt-amperes	megavolt-amps
Megavolt-amperes-reactive	MVAR
megavolts
megawatts	MW
megohms
meters
meters-per-second
miles-per-hour
milliamperes	milliamps
millibars
millimeters
millimeters-of-mercury
Millivolts
Milliwatts
minutes
months
No-Units	No units	No_Units	None
ohms
parts-per-billion
parts-per-million
Pascals
Percent
percent-obscuration-per-foot
percent-obscuration-per-meter
Percent-per-second
percent-relative-humidity	% RH; %RH	Percent RH;	PercentRH
per-hour
per-minute
per-second
pounds-force-per-square-inch	PSI	pounds-force-per-sq-inch
Pounds-mass
pounds-mass-per-hour
pounds-mass-per-minute
pounds-mass-per-second
Power-Factor	PF
psi-per-degrees-fahrenheit
radians
revolutions-per-minute
seconds	Secs	S
square-centimeters
square-feet
square-inches
square-meters
Therms
ton-hours
Tons
Tons-refrigeration
US-gallons	Gallons
us-gallons-per-minute	GPM
Volt-Amperes	Volt-Amps	VA
volt-amperes-reactive	VAR
Volts	Voltage
watt-hours	Wh
Watts	W
watts-per-square-foot
watts-per-square-meter
watts-per-square-meter-degrees-kelvin
weeks
years

 

Appendix D.4. BACnet Specific Statistics

Stat	Description	Resolution
Link Control	A "who-is" link control message was send or received.	It is normal to receive a few link control messages. If the number is higher than the transmit/receive messages, however, there may be a problem with lost communications..
Unsupported Properties	A request for an   unsupported property was received	This is not an error. BACnet clients often poll allproperties of a particular object to determine which properties are supported.
Segmentation Not Supported	Data was requested but the response would have exceeded the maximum size of the APDU and could not be sent using an un-segmented message.	This is not an error – the BACnet client will use a different method to read data from the FieldServer.
Sequence Error	Invoke ID of a reply did not match the Invoke ID of the poll.	You should not see this message. It normally indicates a configuration error.
Write Access Denied	A write to an object was denied.	This typically happens when trying to write to an Input Object that is not Out-Of-Service. It is not possible to write to Input Objects.
Exception Errors	A BACnet Service was denied because it is not supported	This may be a problem on the Client system. Consult the PIC statement to determine what services are supported.